CD Markers
CD61


Last staff update: 21 February 2024 (update in progress)

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PubMed Search: CD61

Pamela Wirth, Ph.D.
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Cite this page: Wirth P. CD61. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cdmarkerscd61.html. Accessed February 26th, 2024.
Definition / general
Essential features
  • CD61, also known as GP3A and β3 integrin, is an adhesion receptor on the membrane of cells with a megakaryocytic lineage (Histol Histopathol 2002;17:347, F1000Res 2016;5:F1000)
  • CD61 forms heterodimer with CD41 known as glycoprotein IIb - IIIa complex
    • CD61 is encoded by ITGB3 gene
      • Dominant integrin on platelets and is highly expressed
      • Important mediator of platelet aggregation
      • Activated glycoprotein IIb - IIIa complex binds fibrinogen or von Willebrand factor to bridge platelets together
  • CD61 can promote invasion and migration in tumors (Am J Transl Res 2019;11:7195)
Terminology
  • β3 integrin (ITGB3)
  • Integrin subunit beta 3
  • GP3A
Pathophysiology
  • Platelet aggregation is mediated by binding of fibrinogen to sites on the glycoprotein IIb - IIIa receptor complex (Biochem J 1995;309:613)
  • Hereditary defect of glycoprotein IIb - IIIa receptor complex causes Glanzmann thrombasthenia, an autosomal recessive bleeding disorder (Transfus Med Rev 2016;30:92)
  • TGFβ is the main upstream factor of integrins and when elevated, leads to increased levels of mesenchymal-like cancer cells (Am J Transl Res 2019;11:7195)
Diagrams / tables

Images hosted on other servers:
Superfamily of integrins

Superfamily of integrins

Clinical features
  • Expressed on macrophages, endothelial cells, fibroblasts, megakaryocytes, osteoclasts, mast cells and platelets
  • Present in normal tissue and tumors (Histol Histopathol 2002;17:347)
Interpretation
  • Membrane, intracellular
  • Cytoplasmic expression in megakaryocytes and platelets
Uses by pathologists
  • Identify platelets, megakaryocytes and platelet thrombi
  • Count platelets in thrombocytopenic patients (Br J Haematol 2001;112:584)
Prognostic factors
Microscopic (histologic) description
  • CD61 is expressed on platelets, megakaryocytes, monocytes, macrophages and endothelial cells (Barclay: The Leucocyte Antigen Factsbook, 2nd Edition, 1997)
    • CD41 interacts with CD61 to form the glycoprotein IIb - IIIa receptor complex
      • Expressed on platelets and megakaryocytes
    • CD41 interacts with CD51 to form the vitronectin receptor
      • Expressed on endothelial cells, monocytes, platelets and osteoclasts
Microscopic (histologic) images

Contributed by Pamela Wirth, Ph.D. (sources: University of Toronto and Human Protein Atlas)
Bone marrow biopsy Bone marrow biopsy

Bone marrow biopsy

Liver cholangiocarcinoma

Liver
cholangiocarcinoma

Kidney adenocarcinoma

Kidney adenocarcinoma

Lung squamous cell carcinoma

Lung squamous cell carcinoma

Colon carcinoma

Colon carcinoma

Positive staining - normal
  • Cytoplasmic staining of normal and abnormal megakaryocytes, platelets, occasional endothelial cells, some myeloid precursor cells
Positive staining - disease
Negative staining
Molecular / cytogenetics description
  • Glanzmann thrombasthenia is caused by a defect in the platelet integrin receptor essential to platelet aggregation and hemostasis
    • Mutations involve missense, nonsense, frameshift or point mutations in ITGA2B or ITGB3 genes located on chromosome 17q21 (Orphanet J Rare Dis 2006;1:10)
Sample pathology report
  • Bone marrow aspirate:
    • Acute leukemia of ambiguous lineage, NOS (see comment)
    • Comment: A 68 year old man presented with suspected leukemia. Bone marrow aspiration revealed 85% blasts with positive expression for CD34, CD7, TdT, CD33, CD117 and CD61, while being negative for MPO, CD19, CD22, CD79a and CD3.
Board review style question #1
An infant is evaluated for bleeding of the gums and ongoing nose bleeds. A complete blood count comes back with normal platelet count but prolonged bleeding time. Evaluation by flow cytometry and IHC indicates markedly decreased CD41 and CD61. Genetic sequencing indicated mutated ITGA2B. What is the most likely diagnosis?

  1. Factor V Leiden
  2. Glanzmann thrombasthenia
  3. Hemophilia B (characterized by deficiency in factor VIII or IX, caused by X linked recessive trait)
  4. Von Willebrand disease
Board review style answer #1
B. Glanzmann thrombasthenia. Significantly decreased levels of CD41 and CD61 is diagnostic for Glanzmann thrombasthenia. Answer A is incorrect because factor V Leiden involves a mutated F5 gene resulting in thrombophilia. Answer C is incorrect because hemophilia B is caused by an X linked recessive trait, not a mutated ITGA or ITGB gene. Answer D is incorrect because von Willebrand disease is caused by variants in the VWF gene.

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Reference: CD61
Board review style question #2

CD61 assists in the identification of which cell type?

  1. Granulocytes
  2. Megakaryocytes
  3. Plasma cells
  4. T cells
Board review style answer #2
B. Megakaryocytes. CD61 is a glycoprotein found on megakaryocytes, platelets and their precursors. Answer A is incorrect because granulocytes are identified by CD66b. Answer C is incorrect because plasma cells are distinguished by their expression of CD38 and CD138. Answer D is incorrect because other CD markers such as CD3, CD4 and CD8 are used to identify this cell type.

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Reference: CD61
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