Immune Thrombocytopenia

Autoimmune MONDO:0008558 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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Definitions

Inheritance

Pathophysiology

Histopathology

Phenotypes

Pathograph

Genes

Treatments

Subtypes

Differentials

Datasets

Trials

Models

References

Deep Research

🏷

Classifications

Harrison's Chapter

⚙

Pathophysiology

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 link Macrophage link

Phagocytosis link

Show evidence (1 reference)

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..."

This review confirms that autoantibody-mediated platelet destruction is central to ITP pathogenesis, with therapeutic strategies targeting Fc receptors and B cells showing efficacy.

Impaired Megakaryopoiesis

Autoantibodies also target megakaryocytes, impairing platelet production. T cell-mediated megakaryocyte damage and cytokine effects further suppress thrombopoiesis.

Megakaryocyte link

Platelet Formation link

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 link

Immune Regulation link

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 link

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.

●

Phenotypes

Thrombocytopenia VERY_FREQUENT Hematological HP:0001873

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

Epistaxis FREQUENT ENT HP:0000421

Easy Bruising FREQUENT Dermatological HP:0000978

💊

Treatments

Corticosteroids

Action: corticosteroid therapy Ontology label: pharmacotherapy MAXO:0000058

Agent: corticosteroid ↗

First-line therapy.

IVIG

Action: intravenous immunoglobulin therapy Ontology label: pharmacotherapy MAXO:0000058

Agent: human immunoglobulin G ↗

For rapid platelet increase, bleeding, or pre-procedure.

Thrombopoietin Receptor Agonists

Action: thrombopoietin receptor agonist therapy Ontology label: pharmacotherapy MAXO:0000058

Agent: thrombopoietin receptor agonist ↗ eltrombopag ↗

Romiplostim, eltrombopag for chronic ITP.

Rituximab

Action: rituximab therapy Ontology label: pharmacotherapy MAXO:0000058

Agent: rituximab ↗

Second-line option.

Splenectomy

Action: splenectomy MAXO:0001077

For refractory disease.

🔬

Biochemical Markers

Platelet Count (Decreased)

Context: Typically <100,000/μL, may be severe <10,000/μL

Antiplatelet Antibodies (Variable)

Context: Not routinely tested; poor sensitivity

MPV (Mean Platelet Volume) (Normal or Increased)

Context: Young platelets released

{ }

Source YAML

click to show

name: Immune Thrombocytopenia
creation_date: '2025-12-19T01:12:52Z'
updated_date: '2026-02-17T21:53:14Z'
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: >-
      This review confirms that autoantibody-mediated platelet destruction is
      central to ITP pathogenesis, with therapeutic strategies targeting Fc
      receptors and B cells showing efficacy.
- 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
- name: Epistaxis
  category: ENT
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Epistaxis
    term:
      id: HP:0000421
      label: Epistaxis
- name: Easy Bruising
  category: Dermatological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Easy Bruisability
    term:
      id: HP:0000978
      label: Bruising susceptibility
biochemical:
- name: Platelet Count
  presence: Decreased
  context: Typically <100,000/μL, may be severe <10,000/μL
- name: Antiplatelet Antibodies
  presence: Variable
  context: Not routinely tested; poor sensitivity
- name: MPV (Mean Platelet Volume)
  presence: Normal or Increased
  context: Young platelets released
treatments:
- name: Corticosteroids
  description: First-line therapy.
  treatment_term:
    preferred_term: corticosteroid therapy
    term:
      id: MAXO:0000058
      label: pharmacotherapy
    therapeutic_agent:
    - preferred_term: corticosteroid
      term:
        id: CHEBI:50858
        label: corticosteroid
- name: IVIG
  description: For rapid platelet increase, bleeding, or pre-procedure.
  treatment_term:
    preferred_term: intravenous immunoglobulin therapy
    term:
      id: MAXO:0000058
      label: pharmacotherapy
    therapeutic_agent:
    - preferred_term: human immunoglobulin G
      term:
        id: NCIT:C80829
        label: Human Immunoglobulin G
- name: Thrombopoietin Receptor Agonists
  description: Romiplostim, eltrombopag for chronic ITP.
  treatment_term:
    preferred_term: thrombopoietin receptor agonist therapy
    term:
      id: MAXO:0000058
      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
- name: Rituximab
  description: Second-line option.
  treatment_term:
    preferred_term: rituximab therapy
    term:
      id: MAXO:0000058
      label: pharmacotherapy
    therapeutic_agent:
    - preferred_term: rituximab
      term:
        id: NCIT:C1702
        label: Rituximab
- name: Splenectomy
  description: For refractory disease.
  treatment_term:
    preferred_term: splenectomy
    term:
      id: MAXO:0001077
      label: splenectomy
classifications:
  harrisons_chapter:
  - classification_value: hematologic disorder
  - classification_value: autoimmune disease
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: []

📚

References & Deep Research

References

DOI:10.1007/s00277-024-05999-z

The effects of complement-independent, autoantibody-induced apoptosis of platelets in immune thrombocytopenia (ITP)