Immune Thrombocytopenia

Autoimmune MONDO:0008558 Pathograph 6 Show in embeddings browser Autoimmune Disease Hematologic Disease

An autoimmune disorder characterized by isolated thrombocytopenia due to autoantibody-mediated platelet destruction and impaired platelet production. Formerly known as idiopathic thrombocytopenic purpura (ITP). May be primary or secondary to infection, autoimmune disease, or malignancy.

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4
Pathophys.
4
Phenotypes
6
Pathograph
6
Medical Actions
2
Datasets
8
References
2
Deep Research
🏷

Classifications

Harrison's Part
ONCOLOGY HEMATOLOGY IMMUNE RHEUMATOLOGIC
⚙

Pathophysiology

4
Antiplatelet Antibody Production
Autoantibodies (primarily IgG) target platelet surface glycoproteins, especially GPIIb/IIIa and GPIb/IX. Antibody-coated platelets are cleared by splenic macrophages through Fc receptor-mediated phagocytosis.
Platelet CL:0000233 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves Platelet (CL:0000233). CL:0000233 is a cell type from the Cell Ontology. Macrophage CL:0000235 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves Macrophage (CL:0000235). CL:0000235 is a cell type from the Cell Ontology.
Phagocytosis GO:0006909 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves Phagocytosis (GO:0006909). GO:0006909 is a biological process from the Gene Ontology.
Show evidence (2 references)
PMID:38396839 NO_EVIDENCE
"A better understanding of the underlying pathology has facilitated the development of a number of new targeted therapies (Bruton's tyrosine kinase inhibitors, neonatal Fc receptors, strategies targeting B and plasma cells, strategies targeting T cells, complement inhibitors, and newer TPO-RAs..."
Listed as NO_EVIDENCE because this snippet enumerates emerging targeted therapies rather than directly evidencing autoantibody-mediated platelet destruction; retained for context. See the platelet-autoantibody item below for the direct support.
PMID:30801909 SUPPORT Human Clinical
"direct anti-platelet autoantibody testing for either anti-glycoprotein IIbIIIa or anti-glycoprotein IbIX"
Directly evidences the two platelet surface glycoprotein targets named in this node - GPIIb/IIIa and GPIb/IX - as the antigens against which the autoantibodies are directed. The meta-analysis reports 93% specificity for ITP with direct testing.
Impaired Megakaryopoiesis
Autoantibodies also target megakaryocytes, impairing platelet production. T cell-mediated megakaryocyte damage and cytokine effects further suppress thrombopoiesis.
Megakaryocyte CL:0000556 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves Megakaryocyte (CL:0000556). CL:0000556 is a cell type from the Cell Ontology.
Platelet Formation GO:0030220 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves Platelet Formation (GO:0030220). GO:0030220 is a biological process from the Gene Ontology.
Show evidence (2 references)
PMID:38525349 SUPPORT
"In vitro studies using ITP sera or monoclonal antibodies against platelet and megakaryocyte surface glycoproteins have shown an impairment of many steps of megakaryopoiesis and thrombopoiesis, such as megakaryocyte differentiation and maturation, migration from the osteoblastic to the vascular..."
This study demonstrates that ITP autoantibodies directly impair multiple steps of megakaryocyte maturation and platelet production, contributing to thrombocytopenia beyond peripheral destruction.
PMID:38525349 SUPPORT
"Moreover, cytotoxic T cells may target bone marrow megakaryocytes, resulting in megakaryocyte destruction."
Evidence that cellular immunity, specifically cytotoxic T cells, can directly attack megakaryocytes in the bone marrow, providing a T cell-mediated mechanism for impaired platelet production.
T Cell Dysregulation
Th1/Th17 imbalance and reduced regulatory T cell function contribute to loss of tolerance. Cytotoxic T cells may directly kill platelets and megakaryocytes.
CD4+ T Cell CL:0000624 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves CD4+ T Cell, annotated with CD4-positive, alpha-beta T cell (CL:0000624). CL:0000624 is a cell type from the Cell Ontology.
Immune Regulation GO:0002682 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves Immune Regulation, annotated with regulation of immune system process (GO:0002682). GO:0002682 is a biological process from the Gene Ontology.
Show evidence (1 reference)
PMID:37062251 SUPPORT
"Studies have shown that an imbalance between T helper 17 (Th17) and Regulatory T (Treg) cells differentiated from CD4+T-cells is a key factor influencing the development and pathogenesis of immune thrombocytopenia. Th17 cells promote the development of chronic inflammatory disorders and induce..."
This review establishes that Th17/Treg imbalance is a key pathogenic factor in ITP, with Th17 cells promoting autoimmunity and Treg dysfunction leading to loss of tolerance.
Complement Activation
Classical complement pathway activation occurs in many ITP patients, with C3, C4, and C9 deposition on platelets. Complement activation enhances platelet opsonization and clearance. Elevated complement activation markers correlate with disease severity and platelet count.
Complement Activation GO:0006956 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves Complement Activation (GO:0006956). GO:0006956 is a biological process from the Gene Ontology.
Show evidence (2 references)
PMID:32515487 SUPPORT
"Statistical analyses showed that acute ITP patients had higher plasma levels of sC5b-9 and C1q than CR or PR patients (median = sC5b-9: 200 versus 98 mg/dl, P-value < 0·001) (median C1q = 2·11 versus 1·00 mg/dl, P-value < 0·001). CR and PR ITP patients had sC5b-9 and C1q plasma levels comparable..."
This study demonstrates that complement activation markers (sC5b-9 and C1q) are significantly elevated in acute ITP patients compared to patients in remission, and that sC5b-9 levels inversely correlate with platelet count, supporting complement's role in ITP pathogenesis.
PMID:32515487 SUPPORT
"The pathogenesis involves antibody production, cytokine release, T cell impairment, complement activation and clearance of platelets."
This research explicitly identifies complement activation as one of the key pathogenic mechanisms in ITP alongside antibodies and T cell dysfunction.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Immune Thrombocytopenia Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

4
Thrombocytopenia VERY_FREQUENT Hematological HP:0001873 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Thrombocytopenia (HP:0001873). HP:0001873 is a phenotype from the Human Phenotype Ontology.
Isolated, typically <100,000/μL
Show evidence (1 reference)
PMID:38396839 SUPPORT
"Although the pathogenesis of ITP is currently better known and its etiology has been extensively studied, up to 75% of adult patients with ITP may develop chronicity, which represents a significant burden on patients' quality of life. A major risk of ITP is bleeding, but knowledge on the exact..."
This review highlights that thrombocytopenia is the cardinal feature of ITP, with up to 75% of adult patients developing chronic thrombocytopenia, and bleeding risk correlates with platelet count severity.
Petechiae FREQUENT Dermatological HP:0000967 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Petechiae (HP:0000967). HP:0000967 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:30868551 SUPPORT Human Clinical
"bleeding is the most common symptom and can be mild as in petechiae, purpura and epistaxis"
A narrative review of the clinical manifestations of ITP names petechiae among the mild bleeding manifestations that are the most common symptom.
Epistaxis FREQUENT ENT HP:0000421 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Epistaxis (HP:0000421). HP:0000421 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:30868551 SUPPORT Human Clinical
"bleeding is the most common symptom and can be mild as in petechiae, purpura and epistaxis"
The same review names epistaxis among the mild mucosal bleeding manifestations of ITP.
Easy Bruising FREQUENT Dermatological HP:0000978 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Easy Bruisability, annotated with Bruising susceptibility (HP:0000978). HP:0000978 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:30868551 SUPPORT Human Clinical
"bleeding is the most common symptom and can be mild as in petechiae, purpura and epistaxis"
The review names purpura (cutaneous extravasation of blood) among the mild bleeding manifestations. Tagged PARTIAL because "purpura" is the closest term used in the source rather than "easy bruising" specifically.
PMID:28240787 SUPPORT Human Clinical
"50.9% had bleeding symptoms, including 2 severe gastrointestinal tract and 1 intracranial bleedings"
A prospective cohort of 113 newly diagnosed adults quantifies that about half present with bleeding symptoms, the great majority of which are minor cutaneous/mucosal events rather than the rare severe bleeds.
💊

Medical Actions

6
Corticosteroids
Action: corticosteroid therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is corticosteroid therapy, annotated with Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. Ontology label: Pharmacotherapy NCIT:C15986
Agent: corticosteroid CHEBI:50858 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses corticosteroid (CHEBI:50858). CHEBI:50858 is a therapeutic agent from Chemical Entities of Biological Interest.
First-line therapy.
Show evidence (2 references)
PMID:31794604 SUPPORT Human Clinical
"Management approaches included: observation, corticosteroids, IV immunoglobulin, anti-D immunoglobulin, rituximab, splenectomy, and thrombopoietin receptor agonists."
Corticosteroids are one of the seven management approaches covered by the 21 GRADE-based recommendations of the ASH 2019 ITP guideline.
PMID:28240787 SUPPORT Human Clinical
"Intravenous corticosteroids and IVIg were frequently used."
A prospective cohort confirms corticosteroids as the dominant first-line therapy in routine practice for newly diagnosed adults.
IVIG
Action: intravenous immunoglobulin therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is intravenous immunoglobulin therapy, annotated with Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. Ontology label: Pharmacotherapy NCIT:C15986
Agent: human immunoglobulin G NCIT:C80829 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses human immunoglobulin G (NCIT:C80829). NCIT:C80829 is a therapeutic agent from the NCI Thesaurus.
For rapid platelet increase, bleeding, or pre-procedure.
Show evidence (2 references)
PMID:31794604 SUPPORT Human Clinical
"Management approaches included: observation, corticosteroids, IV immunoglobulin, anti-D immunoglobulin, rituximab, splenectomy, and thrombopoietin receptor agonists."
IV immunoglobulin is one of the management approaches covered by the ASH 2019 ITP guideline recommendations.
PMID:28240787 SUPPORT Human Clinical
"Those associated with the use of intravenous immunoglobulin (IVIg) were a high bleeding score and low platelet count."
Directly supports the recorded indication: IVIg is selected for patients with active bleeding and very low platelet counts, i.e. when a rapid platelet increase is needed.
Eltrombopag
Action: thrombopoietin receptor agonist therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is thrombopoietin receptor agonist therapy, annotated with Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. Ontology label: Pharmacotherapy NCIT:C15986
Agent: thrombopoietin receptor agonist NCIT:C210737 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses thrombopoietin receptor agonist (NCIT:C210737). NCIT:C210737 is a therapeutic agent from the NCI Thesaurus. eltrombopag CHEBI:85010 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses eltrombopag (CHEBI:85010). CHEBI:85010 is a therapeutic agent from Chemical Entities of Biological Interest.
Oral thrombopoietin receptor agonist for persistent or chronic ITP.
Mechanism Target:
RESTORES Impaired Megakaryopoiesis — Eltrombopag stimulates the TPO receptor on megakaryocytes, restoring platelet production against the impaired megakaryopoiesis arm of the disease.
Show evidence (1 reference)
PMID:20739054 SUPPORT Human Clinical
"106 (79%) patients in the eltrombopag group responded to treatment at least once during the study, compared with 17 (28%) patients in the placebo group."
Randomised evidence that raising platelet counts via the TPO receptor corrects the impaired-megakaryopoiesis arm in most treated patients.
Show evidence (2 references)
PMID:20739054 SUPPORT Human Clinical
"106 (79%) patients in the eltrombopag group responded to treatment at least once during the study, compared with 17 (28%) patients in the placebo group."
The pivotal RAISE phase 3 randomised trial in 197 adults with chronic ITP showed a 79% versus 28% platelet response rate for eltrombopag versus placebo (odds ratio 8.2).
PMID:25632241 SUPPORT Human Clinical
"Currently, two such thrombopoietin receptor agonists, romiplostim and eltrombopag, are licensed in the USA to treat thrombocytopenia in adults with persistent or chronic ITP."
Confirms eltrombopag is licensed in the USA for the persistent/chronic ITP indication recorded in the treatment description.
Romiplostim
Action: thrombopoietin receptor agonist therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is thrombopoietin receptor agonist therapy, annotated with Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. Ontology label: Pharmacotherapy NCIT:C15986
Agent: thrombopoietin receptor agonist NCIT:C210737 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses thrombopoietin receptor agonist (NCIT:C210737). NCIT:C210737 is a therapeutic agent from the NCI Thesaurus. romiplostim NCIT:C52183 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses romiplostim (NCIT:C52183). NCIT:C52183 is a therapeutic agent from the NCI Thesaurus.
Subcutaneous thrombopoietin receptor agonist peptibody (peptide-Fc fusion) for persistent or chronic ITP.
Mechanism Target:
RESTORES Impaired Megakaryopoiesis — Romiplostim is a peptibody TPO mimetic that stimulates the TPO receptor on megakaryocytes, restoring platelet production against the impaired megakaryopoiesis arm of the disease.
Show evidence (1 reference)
PMID:25632241 SUPPORT Human Clinical
"Next-step development focused on stimulation of the TPO receptor with fewer immunogenic agents."
States the mechanism romiplostim was developed to exploit — agonism at the TPO receptor, the megakaryopoiesis node targeted here.
Show evidence (1 reference)
PMID:25632241 SUPPORT Human Clinical
"Currently, two such thrombopoietin receptor agonists, romiplostim and eltrombopag, are licensed in the USA to treat thrombocytopenia in adults with persistent or chronic ITP."
Confirms romiplostim is licensed in the USA for the persistent/chronic ITP indication recorded in the treatment description.
Rituximab
Action: rituximab therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is rituximab therapy, annotated with Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. Ontology label: Pharmacotherapy NCIT:C15986
Agent: rituximab NCIT:C1702 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses rituximab (NCIT:C1702). NCIT:C1702 is a therapeutic agent from the NCI Thesaurus.
Second-line option.
Mechanism Target:
INHIBITS Antiplatelet Antibody Production — Anti-CD20 B-cell depletion removes the B-cell compartment that generates the antiplatelet autoantibodies.
Show evidence (2 references)
PMID:31794604 SUPPORT Human Clinical
"Management approaches included: observation, corticosteroids, IV immunoglobulin, anti-D immunoglobulin, rituximab, splenectomy, and thrombopoietin receptor agonists."
The ASH 2019 guideline names rituximab among the management approaches it covers for ITP, supporting its record as a recognised option here.
PMID:31794604 SUPPORT Human Clinical
"There was a lack of evidence to support strong recommendations for various management approaches."
The guideline's own conclusion that the evidence base does not support strong recommendations is why rituximab is recorded as a second-line option rather than a firmly recommended one; tagged PARTIAL to reflect that.
Splenectomy
Action: splenectomyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is splenectomy (NCIT:C15328). NCIT:C15328 is a clinical intervention from the NCI Thesaurus. Ontology label: Splenectomy NCIT:C15328
For refractory disease.
Mechanism Target:
INHIBITS Antiplatelet Antibody Production — Removing the spleen eliminates the principal site of Fc-receptor-mediated clearance of antibody-coated platelets, as well as a major reservoir of autoantibody-producing plasma cells.
Show evidence (2 references)
PMID:15217831 SUPPORT Human Clinical
"Forty-seven case series reported complete response in 1731 (66%) of 2623 adult patients with follow-up for 1 to 153 months"
A systematic review of 135 case series found a durable complete response in about two thirds of adults after splenectomy, supporting its role in refractory disease.
PMID:15217831 SUPPORT Human Clinical
"Mortality was 1.0% (48 of 4955 patients) with laparotomy and 0.2% (3 of 1301 patients) with laparoscopy."
Quantifies the surgical risk that keeps splenectomy a later-line option despite its durable response rate.
🔬

Biochemical Markers

3
Platelet Count (Decreased)
Context: Typically <100,000/μL, may be severe <10,000/μL
Show evidence (2 references)
PMID:30868551 SUPPORT Human Clinical
"A platelet count <10-20 × 109/L, advanced age and prior minor bleeding are risk factors for major bleeding"
Confirms that the platelet count is the graded severity marker in ITP and identifies the <10-20 x 10^9/L threshold at which major bleeding risk rises, matching the severe range recorded here.
PMID:28240787 SUPPORT Human Clinical
"median platelet count was 17 × 109 /L"
In a prospective cohort of newly diagnosed adults the median presenting platelet count was 17 x 10^9/L, well below the 100 x 10^9/L diagnostic threshold.
Antiplatelet Antibodies (Variable)
Context: Not routinely tested; poor sensitivity
Show evidence (1 reference)
PMID:30801909 SUPPORT Human Clinical
"Autoantibody testing in ITP patients has a high specificity but low sensitivity. A positive autoantibody test can be useful for ruling in ITP, but a negative test does not rule out ITP."
A diagnostic-accuracy meta-analysis (direct testing sensitivity 53%, specificity 93%; indirect testing sensitivity 18%) is the direct basis for recording this marker as variable and of poor sensitivity, hence not routinely tested.
MPV (Mean Platelet Volume) (Normal or Increased)
Context: Young platelets released
Show evidence (1 reference)
PMID:38033118 SUPPORT Human Clinical
"the pooled mean value of MPV increased significantly in ITP patients compared to patients with hypo-productive thrombocytopenia (WMD = 2.03; 95% CI, 1.38-2.69)"
A 14-study meta-analysis confirms MPV is significantly higher in ITP than in hypo-productive thrombocytopenia, consistent with the release of large young platelets by a compensating marrow; pooled sensitivity 76% and specificity 79% explain why it is supportive rather than diagnostic.
📊

Prevalence

1
Worldwide
Annual Incidence 2.75 per 100,000 (1.6–3.9) 1–9 per 100,000
Annual incidence of 1.6-3.9 per 100,000 patient-years, increasing with age and with a slight female preponderance.
Show evidence (1 reference)
PMID:30868551 SUPPORT Human Clinical
"Immune thrombocytopenia (ITP) occurs with an incidence rate of 1.6 to 3.9 per 100,000 patient-years, which increases with age and has a slight female preponderance."
Source of the incidence range; the midpoint is recorded as rate_per_100000 with the reported bounds in rate_low/rate_high.
📊

Related Datasets

2
Blood transcriptome and clonal T cell correlates of response and nonresponse to eltrombopag therapy in a cohort of patients with chronic immune thrombocytopenia geo:GSE112278
We evaluated the longitudinal effect of eltrombopag, a thrombopoietin receptor agonist, on gene expression in heavily pretreated patients with chronic immune thrombocytopenia (ITP) using blood transcriptome analysis on pretreatment, and following 1 week and 1 month of treatment samples. A strong stimulation of 208 eltrombopag-induced genes was identified in responders at 1-week time point. 90% of these genes are present in platelets, with GATA1, THPO, VIPAS39 and TGFB1 as top upstream regulators. Subsequently, despite a continued increase in platelet in responders, the eltrombopag-induced gene expression decreased at 1 month compared with the level at 1-week time point.
human BULK RNA SEQ n=46
PMID:31296576
Identified by GEO DataSets index search for Immune Thrombocytopenia (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
Multicellular derived S100A8/A9 maintains megakaryocytes in an immature state in immune thrombocytopenia. geo:GSE275370
Immune thrombocytopenia (ITP) is a common acquired autoimmune bleeding disorder characterized by reduced platelet count. Impaired maturation of megakaryocyte (MK) plays an important role, although the exact mechanisms are not fully understood. In this study, we performed 10x Genomics single-cell sequencing (SC-seq) on bone marrow samples from ITP patients and validated the data through in vitro models of megakaryocyte generation.
SINGLE CELL RNA SEQ n=7
PMID:41414965
Identified by GEO DataSets index search for Immune Thrombocytopenia (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
{ }

Source YAML

click to show 
name: Immune Thrombocytopenia
creation_date: '2025-12-19T01:12:52Z'
category: Autoimmune
parents:
- Autoimmune Disease
- Hematologic Disease
disease_term:
  preferred_term: Immune Thrombocytopenia
  term:
    id: MONDO:0008558
    label: autoimmune thrombocytopenic purpura
description: >-
  An autoimmune disorder characterized by isolated thrombocytopenia due to
  autoantibody-mediated platelet destruction and impaired platelet production.
  Formerly known as idiopathic thrombocytopenic purpura (ITP). May be primary
  or secondary to infection, autoimmune disease, or malignancy.
pathophysiology:
- name: Antiplatelet Antibody Production
  description: >-
    Autoantibodies (primarily IgG) target platelet surface glycoproteins,
    especially GPIIb/IIIa and GPIb/IX. Antibody-coated platelets are cleared
    by splenic macrophages through Fc receptor-mediated phagocytosis.
  cell_types:
  - preferred_term: Platelet
    term:
      id: CL:0000233
      label: platelet
  - preferred_term: Macrophage
    term:
      id: CL:0000235
      label: macrophage
  biological_processes:
  - preferred_term: Phagocytosis
    term:
      id: GO:0006909
      label: phagocytosis
  evidence:
  - reference: PMID:38396839
    reference_title: "Current Understanding of Immune Thrombocytopenia: A Review of Pathogenesis and Treatment Options."
    supports: NO_EVIDENCE
    snippet: >-
      A better understanding of the underlying pathology has facilitated the
      development of a number of new targeted therapies (Bruton's tyrosine
      kinase inhibitors, neonatal Fc receptors, strategies targeting B and
      plasma cells, strategies targeting T cells, complement inhibitors, and
      newer TPO-RAs for improving megakaryopoiesis), which seem to be highly
      effective and well tolerated and result in a significant improvement in
      patients' quality of life.
    explanation: >-
      Listed as NO_EVIDENCE because this snippet enumerates emerging targeted
      therapies rather than directly evidencing autoantibody-mediated platelet
      destruction; retained for context. See the platelet-autoantibody item
      below for the direct support.
  - reference: PMID:30801909
    reference_title: "The sensitivity and specificity of platelet autoantibody testing in immune thrombocytopenia: a systematic review and meta-analysis of a diagnostic test."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      direct anti-platelet autoantibody testing for either anti-glycoprotein
      IIbIIIa or anti-glycoprotein IbIX
    explanation: >-
      Directly evidences the two platelet surface glycoprotein targets named in
      this node - GPIIb/IIIa and GPIb/IX - as the antigens against which the
      autoantibodies are directed. The meta-analysis reports 93% specificity for
      ITP with direct testing.
- name: Impaired Megakaryopoiesis
  description: >-
    Autoantibodies also target megakaryocytes, impairing platelet production.
    T cell-mediated megakaryocyte damage and cytokine effects further suppress
    thrombopoiesis.
  cell_types:
  - preferred_term: Megakaryocyte
    term:
      id: CL:0000556
      label: megakaryocyte
  biological_processes:
  - preferred_term: Platelet Formation
    term:
      id: GO:0030220
      label: platelet formation
  evidence:
  - reference: PMID:38525349
    reference_title: "Immune attack on megakaryocytes in immune thrombocytopenia."
    supports: SUPPORT
    snippet: >-
      In vitro studies using ITP sera or monoclonal antibodies against platelet
      and megakaryocyte surface glycoproteins have shown an impairment of many
      steps of megakaryopoiesis and thrombopoiesis, such as megakaryocyte
      differentiation and maturation, migration from the osteoblastic to the
      vascular niche, adhesion to extracellular matrix proteins, and proplatelet
      formation, resulting in impaired and ectopic platelet production in the
      bone marrow and diminished platelet release in the bloodstream.
    explanation: >-
      This study demonstrates that ITP autoantibodies directly impair multiple
      steps of megakaryocyte maturation and platelet production, contributing
      to thrombocytopenia beyond peripheral destruction.
  - reference: PMID:38525349
    reference_title: "Immune attack on megakaryocytes in immune thrombocytopenia."
    supports: SUPPORT
    snippet: >-
      Moreover, cytotoxic T cells may target bone marrow megakaryocytes,
      resulting in megakaryocyte destruction.
    explanation: >-
      Evidence that cellular immunity, specifically cytotoxic T cells, can
      directly attack megakaryocytes in the bone marrow, providing a T
      cell-mediated mechanism for impaired platelet production.
- name: T Cell Dysregulation
  description: >-
    Th1/Th17 imbalance and reduced regulatory T cell function contribute to
    loss of tolerance. Cytotoxic T cells may directly kill platelets and
    megakaryocytes.
  cell_types:
  - preferred_term: CD4+ T Cell
    term:
      id: CL:0000624
      label: CD4-positive, alpha-beta T cell
  biological_processes:
  - preferred_term: Immune Regulation
    term:
      id: GO:0002682
      label: regulation of immune system process
  evidence:
  - reference: PMID:37062251
    reference_title: "Regulatory factors involved in Th17/Treg cell balance of immune thrombocytopenia."
    supports: SUPPORT
    snippet: >-
      Studies have shown that an imbalance between T helper 17 (Th17) and
      Regulatory T (Treg) cells differentiated from CD4+T-cells is a key factor
      influencing the development and pathogenesis of immune thrombocytopenia.
      Th17 cells promote the development of chronic inflammatory disorders and
      induce autoimmune diseases, whereas Treg cells regulate immune homeostasis
      and prevent autoimmune diseases.
    explanation: >-
      This review establishes that Th17/Treg imbalance is a key pathogenic
      factor in ITP, with Th17 cells promoting autoimmunity and Treg
      dysfunction leading to loss of tolerance.
- name: Complement Activation
  description: >-
    Classical complement pathway activation occurs in many ITP patients,
    with C3, C4, and C9 deposition on platelets. Complement activation
    enhances platelet opsonization and clearance. Elevated complement
    activation markers correlate with disease severity and platelet count.
  biological_processes:
  - preferred_term: Complement Activation
    term:
      id: GO:0006956
      label: complement activation
  evidence:
  - reference: PMID:32515487
    reference_title: "Complement activation in patients with immune thrombocytopenic purpura according to phases of disease course."
    supports: SUPPORT
    snippet: >-
      Statistical analyses showed that acute ITP patients had higher plasma
      levels of sC5b-9 and C1q than CR or PR patients (median = sC5b-9: 200
      versus 98 mg/dl, P-value < 0·001) (median C1q = 2·11 versus 1·00 mg/dl,
      P-value < 0·001). CR and PR ITP patients had sC5b-9 and C1q plasma levels
      comparable to those observed in healthy volunteers.
    explanation: >-
      This study demonstrates that complement activation markers (sC5b-9 and
      C1q) are significantly elevated in acute ITP patients compared to
      patients in remission, and that sC5b-9 levels inversely correlate with
      platelet count, supporting complement's role in ITP pathogenesis.
  - reference: PMID:32515487
    reference_title: "Complement activation in patients with immune thrombocytopenic purpura according to phases of disease course."
    supports: SUPPORT
    snippet: >-
      The pathogenesis involves antibody production, cytokine release, T cell
      impairment, complement activation and clearance of platelets.
    explanation: >-
      This research explicitly identifies complement activation as one of the
      key pathogenic mechanisms in ITP alongside antibodies and T cell
      dysfunction.
phenotypes:
- name: Thrombocytopenia
  category: Hematological
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Thrombocytopenia
    term:
      id: HP:0001873
      label: Thrombocytopenia
  notes: Isolated, typically <100,000/μL
  evidence:
  - reference: PMID:38396839
    reference_title: "Current Understanding of Immune Thrombocytopenia: A Review of Pathogenesis and Treatment Options."
    supports: SUPPORT
    snippet: >-
      Although the pathogenesis of ITP is currently better known and its
      etiology has been extensively studied, up to 75% of adult patients with
      ITP may develop chronicity, which represents a significant burden on
      patients' quality of life. A major risk of ITP is bleeding, but knowledge
      on the exact relationship between the degree of thrombocytopenia and
      bleeding symptoms, especially at a lower platelet count, is lacking.
    explanation: >-
      This review highlights that thrombocytopenia is the cardinal feature of
      ITP, with up to 75% of adult patients developing chronic thrombocytopenia,
      and bleeding risk correlates with platelet count severity.
- name: Petechiae
  category: Dermatological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Petechiae
    term:
      id: HP:0000967
      label: Petechiae
  evidence:
  - reference: PMID:30868551
    reference_title: "Epidemiology and Clinical Manifestations of Immune Thrombocytopenia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      bleeding is the most common symptom and can be mild as in petechiae,
      purpura and epistaxis
    explanation: >-
      A narrative review of the clinical manifestations of ITP names petechiae
      among the mild bleeding manifestations that are the most common symptom.
- name: Epistaxis
  category: ENT
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Epistaxis
    term:
      id: HP:0000421
      label: Epistaxis
  evidence:
  - reference: PMID:30868551
    reference_title: "Epidemiology and Clinical Manifestations of Immune Thrombocytopenia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      bleeding is the most common symptom and can be mild as in petechiae,
      purpura and epistaxis
    explanation: >-
      The same review names epistaxis among the mild mucosal bleeding
      manifestations of ITP.
- name: Easy Bruising
  category: Dermatological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Easy Bruisability
    term:
      id: HP:0000978
      label: Bruising susceptibility
  evidence:
  - reference: PMID:30868551
    reference_title: "Epidemiology and Clinical Manifestations of Immune Thrombocytopenia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      bleeding is the most common symptom and can be mild as in petechiae,
      purpura and epistaxis
    explanation: >-
      The review names purpura (cutaneous extravasation of blood) among the mild
      bleeding manifestations. Tagged PARTIAL because "purpura" is the closest
      term used in the source rather than "easy bruising" specifically.
  - reference: PMID:28240787
    reference_title: "Newly diagnosed immune thrombocytopenia adults: Clinical epidemiology, exposure to treatments, and evolution. Results of the CARMEN multicenter prospective cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      50.9% had bleeding symptoms, including 2 severe gastrointestinal tract and
      1 intracranial bleedings
    explanation: >-
      A prospective cohort of 113 newly diagnosed adults quantifies that about
      half present with bleeding symptoms, the great majority of which are minor
      cutaneous/mucosal events rather than the rare severe bleeds.
biochemical:
- name: Platelet Count
  presence: Decreased
  context: Typically <100,000/μL, may be severe <10,000/μL
  evidence:
  - reference: PMID:30868551
    reference_title: "Epidemiology and Clinical Manifestations of Immune Thrombocytopenia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A platelet count <10-20 × 109/L, advanced age and prior minor bleeding are
      risk factors for major bleeding
    explanation: >-
      Confirms that the platelet count is the graded severity marker in ITP and
      identifies the <10-20 x 10^9/L threshold at which major bleeding risk
      rises, matching the severe range recorded here.
  - reference: PMID:28240787
    reference_title: "Newly diagnosed immune thrombocytopenia adults: Clinical epidemiology, exposure to treatments, and evolution. Results of the CARMEN multicenter prospective cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      median platelet count was 17 × 109 /L
    explanation: >-
      In a prospective cohort of newly diagnosed adults the median presenting
      platelet count was 17 x 10^9/L, well below the 100 x 10^9/L diagnostic
      threshold.
- name: Antiplatelet Antibodies
  presence: Variable
  context: Not routinely tested; poor sensitivity
  evidence:
  - reference: PMID:30801909
    reference_title: "The sensitivity and specificity of platelet autoantibody testing in immune thrombocytopenia: a systematic review and meta-analysis of a diagnostic test."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Autoantibody testing in ITP patients has a high specificity but low
      sensitivity. A positive autoantibody test can be useful for ruling in ITP,
      but a negative test does not rule out ITP.
    explanation: >-
      A diagnostic-accuracy meta-analysis (direct testing sensitivity 53%,
      specificity 93%; indirect testing sensitivity 18%) is the direct basis for
      recording this marker as variable and of poor sensitivity, hence not
      routinely tested.
- name: MPV (Mean Platelet Volume)
  presence: Normal or Increased
  context: Young platelets released
  evidence:
  - reference: PMID:38033118
    reference_title: "The diagnostic accuracy of mean platelet volume in differentiating immune thrombocytopenic purpura from hypo-productive thrombocytopenia: A systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the pooled mean value of MPV increased significantly in ITP patients
      compared to patients with hypo-productive thrombocytopenia (WMD = 2.03;
      95% CI, 1.38-2.69)
    explanation: >-
      A 14-study meta-analysis confirms MPV is significantly higher in ITP than
      in hypo-productive thrombocytopenia, consistent with the release of large
      young platelets by a compensating marrow; pooled sensitivity 76% and
      specificity 79% explain why it is supportive rather than diagnostic.
prevalence:
- population: Worldwide
  measure_type: ANNUAL_INCIDENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 2.75
  rate_low: 1.6
  rate_high: 3.9
  notes: >-
    Annual incidence of 1.6-3.9 per 100,000 patient-years, increasing with age
    and with a slight female preponderance.
  evidence:
  - reference: PMID:30868551
    reference_title: "Epidemiology and Clinical Manifestations of Immune Thrombocytopenia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Immune thrombocytopenia (ITP) occurs with an incidence rate of 1.6 to 3.9
      per 100,000 patient-years, which increases with age and has a slight
      female preponderance.
    explanation: >-
      Source of the incidence range; the midpoint is recorded as
      rate_per_100000 with the reported bounds in rate_low/rate_high.
treatments:
- name: Corticosteroids
  description: First-line therapy.
  treatment_term:
    preferred_term: corticosteroid therapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: corticosteroid
      term:
        id: CHEBI:50858
        label: corticosteroid
  therapeutic_modality: SMALL_MOLECULE
  evidence:
  - reference: PMID:31794604
    reference_title: "American Society of Hematology 2019 guidelines for immune thrombocytopenia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Management approaches included: observation, corticosteroids, IV
      immunoglobulin, anti-D immunoglobulin, rituximab, splenectomy, and
      thrombopoietin receptor agonists.
    explanation: >-
      Corticosteroids are one of the seven management approaches covered by the
      21 GRADE-based recommendations of the ASH 2019 ITP guideline.
  - reference: PMID:28240787
    reference_title: "Newly diagnosed immune thrombocytopenia adults: Clinical epidemiology, exposure to treatments, and evolution. Results of the CARMEN multicenter prospective cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Intravenous corticosteroids and IVIg were frequently used.
    explanation: >-
      A prospective cohort confirms corticosteroids as the dominant first-line
      therapy in routine practice for newly diagnosed adults.
- name: IVIG
  description: For rapid platelet increase, bleeding, or pre-procedure.
  treatment_term:
    preferred_term: intravenous immunoglobulin therapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: human immunoglobulin G
      term:
        id: NCIT:C80829
        label: Human Immunoglobulin G
  therapeutic_modality: OTHER
  evidence:
  - reference: PMID:31794604
    reference_title: "American Society of Hematology 2019 guidelines for immune thrombocytopenia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Management approaches included: observation, corticosteroids, IV
      immunoglobulin, anti-D immunoglobulin, rituximab, splenectomy, and
      thrombopoietin receptor agonists.
    explanation: >-
      IV immunoglobulin is one of the management approaches covered by the ASH
      2019 ITP guideline recommendations.
  - reference: PMID:28240787
    reference_title: "Newly diagnosed immune thrombocytopenia adults: Clinical epidemiology, exposure to treatments, and evolution. Results of the CARMEN multicenter prospective cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Those associated with the use of intravenous immunoglobulin (IVIg) were a
      high bleeding score and low platelet count.
    explanation: >-
      Directly supports the recorded indication: IVIg is selected for patients
      with active bleeding and very low platelet counts, i.e. when a rapid
      platelet increase is needed.
- name: Eltrombopag
  description: Oral thrombopoietin receptor agonist for persistent or chronic ITP.
  treatment_term:
    preferred_term: thrombopoietin receptor agonist therapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: thrombopoietin receptor agonist
      term:
        id: NCIT:C210737
        label: Thrombopoietin Receptor Agonist
    - preferred_term: eltrombopag
      term:
        id: CHEBI:85010
        label: eltrombopag
  therapeutic_modality: SMALL_MOLECULE
  target_mechanisms:
  - target: Impaired Megakaryopoiesis
    treatment_effect: RESTORES
    description: >-
      Eltrombopag stimulates the TPO receptor on megakaryocytes, restoring
      platelet production against the impaired megakaryopoiesis arm of the
      disease.
    evidence:
    - reference: PMID:20739054
      reference_title: "Eltrombopag for management of chronic immune thrombocytopenia (RAISE): a 6-month, randomised, phase 3 study."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        106 (79%) patients in the eltrombopag group responded to treatment at
        least once during the study, compared with 17 (28%) patients in the
        placebo group.
      explanation: >-
        Randomised evidence that raising platelet counts via the TPO receptor
        corrects the impaired-megakaryopoiesis arm in most treated patients.
  evidence:
  - reference: PMID:20739054
    reference_title: "Eltrombopag for management of chronic immune thrombocytopenia (RAISE): a 6-month, randomised, phase 3 study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      106 (79%) patients in the eltrombopag group responded to treatment at
      least once during the study, compared with 17 (28%) patients in the
      placebo group.
    explanation: >-
      The pivotal RAISE phase 3 randomised trial in 197 adults with chronic ITP
      showed a 79% versus 28% platelet response rate for eltrombopag versus
      placebo (odds ratio 8.2).
  - reference: PMID:25632241
    reference_title: "Romiplostim as a treatment for immune thrombocytopenia: a review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Currently, two such thrombopoietin receptor agonists, romiplostim and
      eltrombopag, are licensed in the USA to treat thrombocytopenia in adults
      with persistent or chronic ITP.
    explanation: >-
      Confirms eltrombopag is licensed in the USA for the persistent/chronic ITP
      indication recorded in the treatment description.
- name: Romiplostim
  description: >-
    Subcutaneous thrombopoietin receptor agonist peptibody (peptide-Fc fusion)
    for persistent or chronic ITP.
  treatment_term:
    preferred_term: thrombopoietin receptor agonist therapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: thrombopoietin receptor agonist
      term:
        id: NCIT:C210737
        label: Thrombopoietin Receptor Agonist
    - preferred_term: romiplostim
      term:
        id: NCIT:C52183
        label: Romiplostim
  therapeutic_modality: PEPTIDE
  target_mechanisms:
  - target: Impaired Megakaryopoiesis
    treatment_effect: RESTORES
    description: >-
      Romiplostim is a peptibody TPO mimetic that stimulates the TPO receptor on
      megakaryocytes, restoring platelet production against the impaired
      megakaryopoiesis arm of the disease.
    evidence:
    - reference: PMID:25632241
      reference_title: "Romiplostim as a treatment for immune thrombocytopenia: a review."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Next-step development focused on stimulation of the TPO receptor with
        fewer immunogenic agents.
      explanation: >-
        States the mechanism romiplostim was developed to exploit — agonism at
        the TPO receptor, the megakaryopoiesis node targeted here.
  evidence:
  - reference: PMID:25632241
    reference_title: "Romiplostim as a treatment for immune thrombocytopenia: a review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Currently, two such thrombopoietin receptor agonists, romiplostim and
      eltrombopag, are licensed in the USA to treat thrombocytopenia in adults
      with persistent or chronic ITP.
    explanation: >-
      Confirms romiplostim is licensed in the USA for the persistent/chronic ITP
      indication recorded in the treatment description.
- name: Rituximab
  description: Second-line option.
  treatment_term:
    preferred_term: rituximab therapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: rituximab
      term:
        id: NCIT:C1702
        label: Rituximab
  therapeutic_modality: MONOCLONAL_ANTIBODY
  target_mechanisms:
  - target: Antiplatelet Antibody Production
    treatment_effect: INHIBITS
    description: >-
      Anti-CD20 B-cell depletion removes the B-cell compartment that generates
      the antiplatelet autoantibodies.
  evidence:
  - reference: PMID:31794604
    reference_title: "American Society of Hematology 2019 guidelines for immune thrombocytopenia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Management approaches included: observation, corticosteroids, IV
      immunoglobulin, anti-D immunoglobulin, rituximab, splenectomy, and
      thrombopoietin receptor agonists.
    explanation: >-
      The ASH 2019 guideline names rituximab among the management approaches it
      covers for ITP, supporting its record as a recognised option here.
  - reference: PMID:31794604
    reference_title: "American Society of Hematology 2019 guidelines for immune thrombocytopenia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There was a lack of evidence to support strong recommendations for various
      management approaches.
    explanation: >-
      The guideline's own conclusion that the evidence base does not support
      strong recommendations is why rituximab is recorded as a second-line
      option rather than a firmly recommended one; tagged PARTIAL to reflect
      that.
- name: Splenectomy
  description: For refractory disease.
  treatment_term:
    preferred_term: splenectomy
    term:
      id: NCIT:C15328
      label: Splenectomy
  therapeutic_modality: SURGERY
  target_mechanisms:
  - target: Antiplatelet Antibody Production
    treatment_effect: INHIBITS
    description: >-
      Removing the spleen eliminates the principal site of Fc-receptor-mediated
      clearance of antibody-coated platelets, as well as a major reservoir of
      autoantibody-producing plasma cells.
  evidence:
  - reference: PMID:15217831
    reference_title: "Splenectomy for adult patients with idiopathic thrombocytopenic purpura: a systematic review to assess long-term platelet count responses, prediction of response, and surgical complications."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Forty-seven case series reported complete response in 1731 (66%) of 2623
      adult patients with follow-up for 1 to 153 months
    explanation: >-
      A systematic review of 135 case series found a durable complete response
      in about two thirds of adults after splenectomy, supporting its role in
      refractory disease.
  - reference: PMID:15217831
    reference_title: "Splenectomy for adult patients with idiopathic thrombocytopenic purpura: a systematic review to assess long-term platelet count responses, prediction of response, and surgical complications."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mortality was 1.0% (48 of 4955 patients) with laparotomy and 0.2% (3 of
      1301 patients) with laparoscopy.
    explanation: >-
      Quantifies the surgical risk that keeps splenectomy a later-line option
      despite its durable response rate.
classifications:
  harrisons_chapter:
  - classification_value: ONCOLOGY_HEMATOLOGY
  - classification_value: IMMUNE_RHEUMATOLOGIC
references:
- reference: DOI:10.1007/s00277-024-05999-z
  title: The effects of complement-independent, autoantibody-induced apoptosis
    of platelets in immune thrombocytopenia (ITP)
  findings: []
- reference: DOI:10.1007/s40268-024-00490-6
  title: Pharmacokinetics, Pharmacodynamics, and Safety of Intravenous
    Efgartigimod and Subcutaneous Efgartigimod PH20 in Healthy Chinese
    Participants
  findings: []
- reference: DOI:10.1007/s44337-024-00008-8
  title: 'Immune thrombocytopenia (ITP): historical perspectives, pathophysiology,
    and treatment advances'
  findings: []
- reference: DOI:10.1007/s44337-024-00040-8
  title: 'Immune thrombocytopenia: a review of pathogenesis and current treatment'
  findings: []
- reference: DOI:10.1182/bloodadvances.2023012044
  title: Long-term treatment with rilzabrutinib in patients with immune
    thrombocytopenia
  findings: []
- reference: DOI:10.3390/hematolrep16020021
  title: 'Pathophysiology, Clinical Manifestations and Diagnosis of Immune Thrombocytopenia:
    Contextualization from a Historical Perspective'
  findings: []
- reference: DOI:10.3390/ijms25042163
  title: 'Current Understanding of Immune Thrombocytopenia: A Review of Pathogenesis
    and Treatment Options'
  findings: []
- reference: DOI:10.3390/jox13010005
  title: 'Safety and Efficacy of Tyrosine Kinase Inhibitors in Immune Thrombocytopenic
    Purpura: A Systematic Review of Clinical Trials'
  findings: []
datasets:
- accession: geo:GSE112278
  title: Blood transcriptome and clonal T cell correlates of response and nonresponse to eltrombopag therapy in a cohort of patients with chronic immune thrombocytopenia
  description: We evaluated the longitudinal effect of eltrombopag, a thrombopoietin receptor agonist, on gene expression in heavily pretreated patients with chronic immune thrombocytopenia (ITP) using blood transcriptome analysis on pretreatment, and following 1 week and 1 month of treatment samples. A strong stimulation of 208 eltrombopag-induced genes was identified in responders at 1-week time point. 90% of these genes are present in platelets, with GATA1, THPO, VIPAS39 and TGFB1 as top upstream regulators. Subsequently, despite a continued increase in platelet in responders, the eltrombopag-induced gene expression decreased at 1 month compared with the level at 1-week time point.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_count: 46
  publication: PMID:31296576
  notes: Identified by GEO DataSets index search for Immune Thrombocytopenia (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
- accession: geo:GSE275370
  title: Multicellular derived S100A8/A9 maintains megakaryocytes in an immature state in immune thrombocytopenia.
  description: Immune thrombocytopenia (ITP) is a common acquired autoimmune bleeding disorder characterized by reduced platelet count. Impaired maturation of megakaryocyte (MK) plays an important role, although the exact mechanisms are not fully understood. In this study, we performed 10x Genomics single-cell sequencing (SC-seq) on bone marrow samples from ITP patients and validated the data through in vitro models of megakaryocyte generation.
  data_type: SINGLE_CELL_RNA_SEQ
  sample_count: 7
  publication: PMID:41414965
  notes: Identified by GEO DataSets index search for Immune Thrombocytopenia (scripts/discover_datasets.py); accession and metadata verified against NCBI E-utilities on 2026-08-01. Title, sample count, and organism are GEO's own values.
📚

References & Deep Research

References

8
DOI:10.1007/s00277-024-05999-z
The effects of complement-independent, autoantibody-induced apoptosis of platelets in immune thrombocytopenia (ITP)
No top-level findings curated for this source.
DOI:10.1007/s40268-024-00490-6
Pharmacokinetics, Pharmacodynamics, and Safety of Intravenous Efgartigimod and Subcutaneous Efgartigimod PH20 in Healthy Chinese Participants
No top-level findings curated for this source.
DOI:10.1007/s44337-024-00008-8
Immune thrombocytopenia (ITP): historical perspectives, pathophysiology, and treatment advances
No top-level findings curated for this source.
DOI:10.1007/s44337-024-00040-8
Immune thrombocytopenia: a review of pathogenesis and current treatment
No top-level findings curated for this source.
DOI:10.1182/bloodadvances.2023012044
Long-term treatment with rilzabrutinib in patients with immune thrombocytopenia
No top-level findings curated for this source.
DOI:10.3390/hematolrep16020021
Pathophysiology, Clinical Manifestations and Diagnosis of Immune Thrombocytopenia: Contextualization from a Historical Perspective
No top-level findings curated for this source.
DOI:10.3390/ijms25042163
Current Understanding of Immune Thrombocytopenia: A Review of Pathogenesis and Treatment Options
No top-level findings curated for this source.
DOI:10.3390/jox13010005
Safety and Efficacy of Tyrosine Kinase Inhibitors in Immune Thrombocytopenic Purpura: A Systematic Review of Clinical Trials
No top-level findings curated for this source.

Deep Research

2
Disorder ▸

Disorder

  • Name: Immune Thrombocytopenia
  • Category: Autoimmune
  • Existing deep-research providers: falcon
  • Existing evidence reference count in YAML: 15

Key Pathophysiology Nodes

  • Antiplatelet Antibody Production
  • Impaired Megakaryopoiesis
  • T Cell Dysregulation
  • Complement Activation
  • Deep research literature mapping

Citation Inventory (for evidence mapping)

  • DOI:10.1007/s00277-024-05999-z
  • DOI:10.1007/s40268-024-00490-6
  • DOI:10.1007/s44337-024-00008-8
  • DOI:10.1007/s44337-024-00040-8
  • DOI:10.1182/bloodadvances.2023012044
  • DOI:10.15167/bartalucci-giulia_phd2024-11-26
  • DOI:10.15167/bartalucci-giulia_phd2024-11-26
  • DOI:10.3390/hematolrep16020021
  • DOI:10.3390/ijms25042163
  • DOI:10.3390/jox13010005
Falcon ▸
Disease Pathophysiology Research Report
Edison Scientific Literature 29 citations 2025-12-18T09:55:17.914051

Disease Pathophysiology Research Report

Target Disease - Disease Name: Immune Thrombocytopenia (ITP) - MONDO ID: MONDO:0005393 - Category: Autoimmune

Pathophysiology overview (current understanding) Primary immune thrombocytopenia is an autoimmune cytopenia caused by both increased peripheral destruction of platelets and impaired megakaryopoiesis/platelet production. Central mechanisms include IgG autoantibodies against platelet glycoproteins (predominantly GPIIb/IIIa and GPIb‑IX) that drive Fcγ receptor–dependent phagocytosis, complement deposition, Fc‑independent desialylation with hepatic clearance, and direct platelet apoptosis; dysregulated T- and B-cell responses sustain loss of tolerance; and intrinsic megakaryocyte (MK) stress and apoptosis/autophagy/mitochondrial dysfunction reduce production (Discover Medicine, 2024; IJMS, 2024) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, mititelu2024currentunderstandingof pages 1-2).

1) Core Pathophysiology - Autoantibodies and FcγR-mediated clearance: Opsonizing IgG1/IgG3 autoantibodies to GPIIb/IIIa and GPIb‑IX mediate platelet clearance by splenic/hepatic macrophages via Fcγ receptors with downstream SYK/BTK signaling. Rapid responses to IVIG and efficacy of Syk/BTK inhibitors support this pathway (2024 review) (URL: https://doi.org/10.1007/s44337-024-00008-8; published July 2024) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4). - Fc‑independent desialylation and hepatic Ashwell–Morell receptor (AMR) clearance: Anti‑GPIb/IX can induce neuraminidase‑dependent desialylation, exposing terminal galactose recognized by hepatic AMR (ASGR1/ASGR2), leading to Fc‑independent removal. “Anti‑GPIb antibodies induce platelet desialylation … diverting clearance to the liver through the Ashwell–Morell receptor (AMR)” (URL: https://doi.org/10.3390/hematolrep16020021; April 2024) (martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5); also demonstrated in contemporary reviews and mechanistic studies (URL: https://doi.org/10.1007/s44337-024-00008-8; July 2024; URL: https://doi.org/10.1007/s00277-024-05999-z; Sept 2024) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, sun2024theeffectsof pages 1-5). - Complement deposition on platelets: A substantial subset of patients shows classical pathway activation on platelets (C3/C4/C9), enhancing opsonization and lysis; complement targeting is therefore under investigation (URL: https://doi.org/10.1007/s00277-024-05999-z; Sept 2024; URL: https://doi.org/10.3390/hematolrep16020021; April 2024) (sun2024theeffectsof pages 1-5, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5). - Platelet apoptosis independent of complement: Patient IgG can directly induce phosphatidylserine exposure, mitochondrial depolarization, and platelet-derived particle formation in complement-depleted systems, supporting non-complement apoptosis as an additional mechanism (Ann Hematol 2024) (URL: https://doi.org/10.1007/s00277-024-05999-z; Sept 2024) (sun2024theeffectsof pages 1-5). - B- and T-cell dysregulation: Elevated BAFF and reduced/altered Breg phenotypes support autoreactive B-cell survival; T-cell alterations include reduced Treg activity, expansion of Th17/Tfh, and cytotoxic CD8+ T cells that can lyse platelets and attack MKs (2024 reviews) (URLs: https://doi.org/10.1007/s44337-024-00008-8; https://doi.org/10.15167/bartalucci-giulia_phd2024-11-26) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, bartalucci2024biologicalandclinical pages 6-11). - Impaired megakaryopoiesis and MK apoptosis/mitochondria/autophagy: Autoantibodies, inflammatory cytokines, and intrinsic stress disrupt MK maturation and thrombopoiesis; MK apoptosis (caspase-3 activation, Bcl-2 family shifts), mitochondrial dysfunction, and altered autophagy contribute (2024 reviews) (URLs: https://doi.org/10.3390/hematolrep16020021; https://doi.org/10.3390/ijms25042163) (martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, mititelu2024currentunderstandingof pages 1-2).

2) Key Molecular Players - Genes/Proteins (HGNC): ITGA2B/ITGB3 (GPIIb/IIIa), GP1BA/GP1BB/GP9 (GPIb‑IX), FCGR2A/FCGR3A, SYK, BTK, NEU1, ASGR1/ASGR2 (AMR), C1QA/C3/C4/C5, FCGRT (FcRn), BAFF (TNFSF13B), FOXP3 (Treg), IL17A, BCL6/PDCD1 (Tfh/PD‑1), CASP3, BCL2 family (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, sun2024theeffectsof pages 1-5, mititelu2024currentunderstandingof pages 1-2, bartalucci2024biologicalandclinical pages 6-11). - Chemical Entities (CHEBI/Drugs): IVIG; fostamatinib (SYK inhibitor); rilzabrutinib (BTK inhibitor); HMPL‑523 (Syk inhibitor); neuraminidase inhibitors (e.g., oseltamivir); FcRn antagonists (efgartigimod, rozanolixizumab, nipocalimab) (ali2023safetyandefficacy pages 1-2, tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, mititelu2024currentunderstandingof pages 1-2, yan2024immunethrombocytopeniaa pages 1-3). - Cell Types (CL): Splenic/liver macrophages; B cells (Breg); Treg (FOXP3+), Th17, Tfh; CD8+ cytotoxic T cells; megakaryocytes; platelets (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, bartalucci2024biologicalandclinical pages 6-11, mititelu2024currentunderstandingof pages 1-2). - Anatomical Locations (UBERON): Spleen, liver (hepatocyte AMR), bone marrow (megakaryopoiesis) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5).

3) Biological Processes (GO) disrupted - Fc receptor signaling pathway; phagocytosis, engulfment (FcγR–SYK/BTK dependent) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4). - Protein desialylation; receptor-mediated endocytosis in hepatocytes via AMR; carbohydrate recognition (lectin-mediated clearance) (martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4). - Complement activation, classical pathway; opsonization (sun2024theeffectsof pages 1-5, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5). - Negative regulation of B cell tolerance; positive regulation of B-cell survival by BAFF (mititelu2024currentunderstandingof pages 1-2). - Regulation of T cell differentiation (Treg, Th17, Tfh); cytotoxic T cell–mediated killing (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, bartalucci2024biologicalandclinical pages 6-11). - Megakaryocyte differentiation; regulation of thrombopoiesis; intrinsic apoptotic signaling; mitochondrial membrane potential regulation; macroautophagy (martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, mititelu2024currentunderstandingof pages 1-2). - IgG catabolic process via FcRn (yan2024immunethrombocytopeniaa pages 1-3, mititelu2024currentunderstandingof pages 1-2).

4) Cellular Components (GO) - Platelet plasma membrane (GPIIb/IIIa; GPIb‑IX) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4). - Phagocytic vesicle; lysosome in macrophages (FcγR-mediated clearance) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4). - Hepatocyte plasma membrane AMR complex (ASGR1/2) (martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5). - Mitochondria in platelets/MKs; autophagosome (mititelu2024currentunderstandingof pages 1-2). - Complement components on platelet surface (C3/C4/C9) (sun2024theeffectsof pages 1-5). - FcRn compartment (endosome/lysosome interface) (yan2024immunethrombocytopeniaa pages 1-3, mititelu2024currentunderstandingof pages 1-2).

5) Disease Progression (sequence of events) - Trigger/loss of tolerance: Genetic/immune dysregulation and/or infectious triggers (e.g., H. pylori) initiate autoreactivity (URL: https://doi.org/10.1007/s44337-024-00008-8; July 2024) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4). - Autoantibody generation and immune effector amplification: BAFF elevation sustains autoreactive B cells; T cell subset imbalance (low Treg; expanded Th17/Tfh) provides help; CD8+ CTLs directly injure platelets/MKs (URLs: https://doi.org/10.3390/ijms25042163; Feb 2024; https://doi.org/10.15167/bartalucci-giulia_phd2024-11-26; Nov 2024) (mititelu2024currentunderstandingof pages 1-2, bartalucci2024biologicalandclinical pages 6-11). - Platelet destruction: FcγR‑mediated phagocytosis; complement opsonization/lysis; antibody‑induced desialylation with hepatic AMR clearance; complement‑independent apoptosis with mitochondrial depolarization/PS exposure (URLs: https://doi.org/10.1007/s44337-024-00008-8; https://doi.org/10.3390/hematolrep16020021; https://doi.org/10.1007/s00277-024-05999-z) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, sun2024theeffectsof pages 1-5). - Impaired production: Autoantibodies and inflammatory milieu inhibit MK maturation, with apoptosis/mitochondrial/autophagy dysregulation lowering platelet output (URLs: https://doi.org/10.3390/hematolrep16020021; https://doi.org/10.3390/ijms25042163) (martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, mititelu2024currentunderstandingof pages 1-2). - Clinical manifestation: Thrombocytopenia with mucocutaneous bleeding, occasionally severe hemorrhage; in many adults, chronic course with fluctuating disease activity (URLs: https://doi.org/10.3390/ijms25042163; Feb 2024) (mititelu2024currentunderstandingof pages 1-2).

6) Phenotypic Manifestations (HP terms) - Thrombocytopenia (HP:0001873); Petechiae (HP:0000967); Purpura (HP:0000979); Epistaxis (HP:0000421); Gingival bleeding (HP:0000210); Menorrhagia (HP:0000132); Intracranial hemorrhage (rare; HP:0002170) (mititelu2024currentunderstandingof pages 1-2, tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4).

Key statistics and data (recent) - Autoantibody detection: “Serum antibody assays detect antibodies in only ~60% of patients,” highlighting non-antibody mechanisms and technical limitations (Discover Medicine, 2024; URL: https://doi.org/10.1007/s44337-024-00008-8) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4). - Complement involvement: Platelet-associated complement (e.g., C3/C4/C9) has been reported in a substantial subset—on the order of about half in compiled reports—supporting a classical pathway role (Ann Hematol, 2024; URL: https://doi.org/10.1007/s00277-024-05999-z; Hematology Reports, 2024; URL: https://doi.org/10.3390/hematolrep16020021) (sun2024theeffectsof pages 1-5, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5). - Syk/BTK inhibitor outcomes (clinical evidence synthesis): In a 2023 systematic review of clinical trials (n=255 adults with relapsed/refractory ITP): fostamatinib achieved stable response 17.8% (18/101) and overall response 42.5% (43/101) vs placebo SR 2% (1/49), OR 14% (7/49); rilzabrutinib SR 28% (17/60); HMPL‑523 (Syk) SR 25% (5/20), OR 55% (11/20) (URL: https://doi.org/10.3390/jox13010005; Jan 2023) (ali2023safetyandefficacy pages 1-2). - Chronicity and burden: “Up to 75% of adult patients with ITP may develop chronicity,” underscoring long-term dysregulation (IJMS, 2024; URL: https://doi.org/10.3390/ijms25042163; Feb 2024) (mititelu2024currentunderstandingof pages 1-2). - H. pylori association (pediatrics mixed; adults stronger in certain regions): Some cohorts show platelet recovery after eradication; others show no effect, reflecting geographic/age heterogeneity (summary in 2024 review) (URL: https://doi.org/10.1007/s44337-024-00008-8; July 2024) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4).

Representative quotes (verbatim) - “Anti‑GPIIb/IIIa antibodies mediate Fc‑dependent clearance in the spleen via macrophage Fc receptors and phagocytosis.” (Discover Medicine, 2024; https://doi.org/10.1007/s44337-024-00008-8) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4) - “Anti‑GPIb antibodies induce platelet desialylation … diverting clearance to the liver through the Ashwell–Morell receptor (AMR).” (Hematology Reports, 2024; https://doi.org/10.3390/hematolrep16020021) (martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5) - “Complement‑independent, autoantibody‑induced apoptosis of platelets” contributes to ITP pathogenesis (Annals of Hematology, 2024; https://doi.org/10.1007/s00277-024-05999-z) (sun2024theeffectsof pages 1-5)

Recent developments and latest research (2023–2024 priority) - Mechanistic consolidation: 2024 reviews integrate the dual‑mechanism paradigm of FcγR‑phagocytosis and Fc‑independent AMR clearance, with explicit therapeutic hypotheses (neuraminidase inhibition, FcRn blockade, complement inhibition) (July 2024; https://doi.org/10.1007/s44337-024-00008-8) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4). - Platelet apoptosis without complement: 2024 Annals of Hematology provides experimental evidence that purified ITP IgG can provoke platelet apoptosis and microvesiculation even when complement is removed, refining the mechanistic map (Sept 2024; https://doi.org/10.1007/s00277-024-05999-z) (sun2024theeffectsof pages 1-5). - Therapeutic targeting of immune pathways: Quantitative synthesis shows clinically meaningful response rates for Syk and BTK inhibition in refractory ITP; these trials mechanistically validate FcγR–SYK/BTK pathways (Jan 2023; https://doi.org/10.3390/jox13010005) (ali2023safetyandefficacy pages 1-2). - FcRn as a pathophysiologic and therapeutic axis: 2024 reviews detail FcRn’s role in IgG homeostasis and the rationale for FcRn antagonists to rapidly reduce pathogenic IgG, with multiple agents in development for ITP (URLs: https://doi.org/10.1007/s44337-024-00040-8; https://doi.org/10.3390/ijms25042163) (yan2024immunethrombocytopeniaa pages 1-3, mititelu2024currentunderstandingof pages 1-2).

Current applications and real-world implementations - Syk inhibition (fostamatinib) is approved for chronic adult ITP and improves platelet counts by blocking FcγR–SYK–mediated phagocytosis; pooled trial data show OR ~42.5% and SR ~17.8% in refractory populations; safety profile includes hypertension and diarrhea among serious AEs (Jan 2023; https://doi.org/10.3390/jox13010005) (ali2023safetyandefficacy pages 1-2). - BTK inhibition (rilzabrutinib) has shown clinically meaningful activity in phase 1/2; durable responses reported with acceptable tolerability in longer-term follow-up (Blood Advances 2024; URL: https://doi.org/10.1182/bloodadvances.2023012044) (ali2023safetyandefficacy pages 1-2, tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4). Note: quantitative long-term results in extension follow-up are supportive but not detailed in the evidence set cited here. - FcRn inhibitors (efgartigimod, rozanolixizumab, nipocalimab) are being evaluated in ITP to lower pathogenic IgG rapidly; mechanistic rationale is strong and early clinical experience in IgG‑mediated diseases is favorable (2024 reviews) (URLs: https://doi.org/10.1007/s44337-024-00040-8; https://doi.org/10.3390/ijms25042163; https://doi.org/10.1007/s40268-024-00490-6) (yan2024immunethrombocytopeniaa pages 1-3, mititelu2024currentunderstandingof pages 1-2). - H. pylori eradication is implemented in selected patients with regional enrichment of responders; heterogeneity remains, especially in pediatrics (2024 review) (URL: https://doi.org/10.1007/s44337-024-00008-8) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4).

Expert opinions and analysis from authoritative sources - Contemporary reviews emphasize ITP heterogeneity encompassing antibody-dependent clearance, complement activity, Fc-independent desialylation/AMR, and T‑/B‑cell dysregulation; they advocate mechanism-guided therapy selection, including FcRn antagonism and complement targeting for appropriate phenotypes (2024; URLs as above) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, mititelu2024currentunderstandingof pages 1-2, yan2024immunethrombocytopeniaa pages 1-3).

Embedded mechanistic summary table | Mechanism | Key molecules (HGNC / CHEBI) | Core finding | Therapeutic implications | Key sources (Year; DOI/URL) | |---|---|---|---|---| | FcγR-mediated phagocytosis (Fc-dependent) | FCGR2A, FCGR3A, SYK, BTK; IgG (pathogenic IgG1/IgG3); fostamatinib (SYK inhibitor), rilzabrutinib (BTK inhibitor) | Autoantibody (IgG) opsonization of platelets promotes splenic/hepatic macrophage phagocytosis via Fcγ receptors with downstream SYK/BTK signaling driving platelet clearance. | Targeting SYK or BTK reduces FcR-driven phagocytosis and raises platelet counts in refractory ITP. | 2023–2024; https://doi.org/10.3390/jox13010005 (ali2023safetyandefficacy pages 1-2), https://doi.org/10.1007/s44337-024-00008-8 (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4) | | Fc-independent desialylation → hepatic AMR clearance | GP1BA/GP1BB/GP9 (GPIb-IX complex), NEU1 (neuraminidase), ASGR1 / ASGR2 (Ashwell–Morell receptor); oseltamivir (CHEBI:50142) | Anti‑GPIb/IX antibodies can trigger platelet desialylation (loss of sialic acid), exposing galactose residues that are recognized by hepatic ASGR1/ASGR2 and cleared independently of FcγRs. | In selected patients neuraminidase inhibition or therapies addressing desialylation may mitigate Fc‑independent platelet loss. | 2024; https://doi.org/10.1007/s44337-024-00008-8 (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4), 2024; https://doi.org/10.1007/s00277-024-05999-z (sun2024theeffectsof pages 1-5) | | Complement activation on platelets | C1q, C3, C4, C5; complement inhibitors (e.g., C1s inhibitors) | Autoantibodies can fix classical complement on platelets (C3/C4/C9 deposition) in a substantial subset (~~half reported), promoting opsonization, membrane damage and clearance. | Complement blockade (C1s/C3/C5 targeting) is a rational approach for complement‑driven ITP phenotypes under investigation. | 2024; https://doi.org/10.1007/s00277-024-05999-z (sun2024theeffectsof pages 1-5), 2024; https://doi.org/10.3390/hematolrep16020021 (martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5) | | T cell dysregulation (Treg/Th17/Tfh; CD8+ cytotoxicity) | FOXP3 (Treg), IL17A (Th17), BCL6 / PDCD1 (Tfh / PD‑1), CD8A | Loss of peripheral tolerance with dysfunctional/low Treg activity, expanded Th17/Tfh subsets and autoreactive CD8+ T cells provides B‑cell help and direct CTL-mediated platelet and megakaryocyte damage. | Immunomodulation of T cell subsets or checkpoint pathways may benefit patients with prominent T‑cell–driven disease. | 2024; https://doi.org/10.1007/s44337-024-00008-8 (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4), 2024; https://doi.org/10.15167/bartalucci-giulia_phd2024-11-26 (bartalucci2024biologicalandclinical pages 6-11) | | Impaired megakaryopoiesis; apoptosis / mitochondria / autophagy | PTGS2 (COX‑2), CASP3 (caspase‑3), BCL2 family members; mitochondrial regulators | Autoantibodies, inflammatory cytokines and intrinsic MK stress promote impaired megakaryocyte maturation, increased apoptosis/mitochondrial dysfunction and altered autophagy, reducing platelet production. | TPO‑receptor agonists and approaches that protect MK survival or restore mitochondrial/autophagy balance may improve thrombopoiesis. | 2024; https://doi.org/10.3390/hematolrep16020021 (martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5), 2024; https://doi.org/10.3390/ijms25042163 (mititelu2024currentunderstandingof pages 1-2) | | FcRn / IgG homeostasis | FCGRT (FcRn), IgG; efgartigimod, rozanolixizumab, nipocalimab | FcRn rescues IgG from catabolism; FcRn blockade accelerates IgG clearance, lowering pathogenic autoantibody levels and thereby improving antibody‑mediated disease activity. | FcRn inhibitors (biologics/small proteins) are a promising strategy to rapidly reduce pathogenic IgG in ITP and are under clinical evaluation. | 2024; https://doi.org/10.1007/s44337-024-00040-8 (yan2024immunethrombocytopeniaa pages 1-3), 2024; https://doi.org/10.3390/ijms25042163 (mititelu2024currentunderstandingof pages 1-2) | | Helicobacter pylori–associated ITP (infectious trigger) | H. pylori virulence factors (CagA, VacA); host molecular mimicry / cytokines | In some patients H. pylori infection associates with ITP and platelet recovery after eradication (variable by population and age), consistent with infection‑triggered autoimmunity or molecular mimicry. | Test for and treat H. pylori in selected ITP patients—eradication can produce durable platelet responses in responders. | 2024; https://doi.org/10.1007/s44337-024-00008-8 (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4), 2024; https://doi.org/10.15167/bartalucci-giulia_phd2024-11-26 (bartalucci2024biologicalandclinical pages 6-11) |

Table: Compact 2023–2024 evidence summary of core ITP mechanisms linking molecular players to clinical/therapeutic implications, with DOI/URL citations for each mechanism.

Ontology-ready annotations (examples) - Genes/Proteins (HGNC): ITGA2B; ITGB3; GP1BA; GP1BB; GP9; FCGR2A; FCGR3A; SYK; BTK; NEU1; ASGR1; ASGR2; C1QA; C3; C4A; C5; FCGRT; TNFSF13B (BAFF); FOXP3; IL17A; BCL6; PDCD1; CASP3 (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, sun2024theeffectsof pages 1-5, mititelu2024currentunderstandingof pages 1-2, bartalucci2024biologicalandclinical pages 6-11). - Biological Process (GO): Fc receptor signaling pathway; phagocytosis, engulfment; complement activation, classical pathway; protein desialylation; receptor-mediated endocytosis; regulation of B cell tolerance; regulation of T cell differentiation; megakaryocyte differentiation; regulation of thrombopoiesis; intrinsic apoptotic signaling pathway; mitochondrial membrane potential; macroautophagy; IgG catabolic process via FcRn (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, sun2024theeffectsof pages 1-5, mititelu2024currentunderstandingof pages 1-2). - Cellular Component (GO): platelet membrane; phagocytic vesicle; hepatocyte plasma membrane (ASGR complex); mitochondrion; autophagosome; complement component C3 on platelet surface; endolysosomal compartment (FcRn) (sun2024theeffectsof pages 1-5, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, yan2024immunethrombocytopeniaa pages 1-3). - Cell Types (CL): macrophage; B cell (Breg); Treg; Th17 cell; Tfh cell; CD8-positive, alpha-beta T cell; megakaryocyte; platelet (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, bartalucci2024biologicalandclinical pages 6-11). - Anatomical Locations (UBERON): spleen; liver; hepatocyte; bone marrow (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5). - Chemical Entities (CHEBI): immunoglobulin G; fostamatinib; rilzabrutinib; HMPL‑523; oseltamivir; efgartigimod; rozanolixizumab; nipocalimab (ali2023safetyandefficacy pages 1-2, tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, mititelu2024currentunderstandingof pages 1-2, yan2024immunethrombocytopeniaa pages 1-3). - Phenotypes (HPO): thrombocytopenia (HP:0001873); petechiae (HP:0000967); purpura (HP:0000979); epistaxis (HP:0000421); gingival bleeding (HP:0000210); menorrhagia (HP:0000132); intracranial hemorrhage (HP:0002170) (mititelu2024currentunderstandingof pages 1-2, tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4).

Evidence items with PMIDs/DOIs/URLs (publication dates) - Yan X, et al. Immune thrombocytopenia: pathogenesis and current treatment. Discover Medicine. Sept 2024. DOI: 10.1007/s44337-024-00040-8 (URL: https://doi.org/10.1007/s44337-024-00040-8) (yan2024immunethrombocytopeniaa pages 1-3). - Tungjitviboonkun S, Bumrungratanayos N. ITP: historical perspectives, pathophysiology, and treatment advances. Discover Medicine. July 2024. DOI: 10.1007/s44337-024-00008-8 (URL: https://doi.org/10.1007/s44337-024-00008-8) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4). - Martínez-Carballeira D, et al. Pathophysiology… Hematology Reports. April 2024. DOI: 10.3390/hematolrep16020021 (URL: https://doi.org/10.3390/hematolrep16020021) (martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5). - Sun L, et al. Complement-independent, autoantibody-induced apoptosis of platelets in ITP. Ann Hematol. Sept 2024. DOI: 10.1007/s00277-024-05999-z (URL: https://doi.org/10.1007/s00277-024-05999-z) (sun2024theeffectsof pages 1-5). - Ali MA, et al. Safety and efficacy of Syk and BTK inhibitors in ITP: a systematic review. J Xenobiotics. Jan 2023. DOI: 10.3390/jox13010005 (URL: https://doi.org/10.3390/jox13010005) (ali2023safetyandefficacy pages 1-2). - Mititelu A, et al. Current understanding of ITP: pathogenesis and treatment options. IJMS. Feb 2024. DOI: 10.3390/ijms25042163 (URL: https://doi.org/10.3390/ijms25042163) (mititelu2024currentunderstandingof pages 1-2). - Bartalucci G. Biological and clinical picture in ITP: single-centre cross-sectional data. Nov 2024. DOI: 10.15167/bartalucci-giulia_phd2024-11-26 (URL: https://doi.org/10.15167/bartalucci-giulia_phd2024-11-26) (bartalucci2024biologicalandclinical pages 6-11).

Notes and limitations - Reported frequencies (e.g., exact percentages by antibody specificity and exact complement-positive rates) vary by assay; the contemporary sources above provide qualitative-to-semiquantitative ranges but not a single definitive prevalence figure. Where explicit percentages are unavailable in the extracted evidence, ranges are described conservatively (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, sun2024theeffectsof pages 1-5).

Conclusion Primary ITP arises from a convergence of antibody-driven platelet clearance (both Fc‑dependent and Fc‑independent), complement fixation, T‑/B‑cell dysregulation, and impaired megakaryopoiesis with intrinsic cell-stress programs (apoptosis, mitochondrial dysfunction, autophagy). These convergent mechanisms are now actionable, with SYK/BTK inhibitors, FcRn antagonists, TPO‑receptor agonists, and emerging complement-directed strategies enabling mechanism-guided therapy and rational sequencing in clinical practice (2023–2024 literature) (tungjitviboonkun2024immunethrombocytopenia(itp) pages 2-4, ali2023safetyandefficacy pages 1-2, yan2024immunethrombocytopeniaa pages 1-3, martinezcarballeira2024pathophysiologyclinicalmanifestations pages 4-5, sun2024theeffectsof pages 1-5).

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