CD Markers
CD45


Topic Completed: 1 October 2013

Minor changes: 8 October 2020

Copyright: 2003-2020, PathologyOutlines.com, Inc.

PubMed Search: CD45[title]

Related topics: CD45RO, CD45RA, CD45RB, CD45RC

Nat Pernick, M.D.
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Cite this page: Pernick N. CD45. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/cdmarkerscd45.html. Accessed October 20th, 2020.
Definition / general
  • Commonly used marker of hematopoietic cells except erythrocytes and platelets; plays a major role in immune system
  • Also called leukocyte common antigen (LCA), protein tyrosine phosphatase (References: OMIM #151460)
Pathophysiology
  • High molecular weight transmembrane protein with intrinsic tyrosine phosphatase activity
  • Heavily glycosylated and expressed at high levels on nucleated hematopoietic cells
  • Disruption of the equilibrium between protein tyrosine kinase and phosphatase activity (from CD45 and others) can result in immunodeficiency, autoimmunity or malignancy (Immunol Rev 2009;228:288)
  • An essential regulator of T and B cell antigen receptor-mediated activation
  • Also required for thymic selection
  • Major component of glycocalyx
Clinical features
    Different subsets of hematopoietic cells express different CD45 isoforms due to variable exon splicing, which can change in response to cytokines:
    • CD45RA: naive / resting T cells, medullary thymocytes
    • CD45RO: memory / activated T cells, cortical thymocytes
    • Also CD45RB and CD45RC

  • Loss of CD45 mutations cause severe combined immunodeficiency-autosomal recessive, T cell negative, B cell positive and NK cell positive (OMIM #608971); patients have a defect in B/T cell development, lymphopenia and deficiency in humoral and cell-mediated immunity
  • 77C to G mutation may increase intensity of T cell receptor signaling (J Immunol 2006;176:931) and cause some cases of systemic sclerosis (Genes Immun 2003;4:168), multiple sclerosis (controversial, Nat Genet 2000;26:495) and autoimmune hepatitis (Genes Immun 2003;4:79)
  • Loss of CD45 activity in lymphocytes of elderly may cause T cell dysfunction (Mech Ageing Dev 2003;124:191)
  • Necrotic lymphomas are still CD45+, but occasional necrotic carcinomas may also be CD45+ (Am J Clin Pathol 1998;110:641)
Uses by pathologists
Microscopic (histologic) images

Cases #284, #140, #130 and #151

Nodular lymphocyte
predominant
Hodgkin lymphoma

Leukemia cutis

Myeloid sarcoma of fibula

Leukemic vasculitis
in the context of
leukemia cutis



Images hosted on other servers:
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Diffuse large B cell lymphoma (urine cytology)

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Diffuse large B cell lymphoma (H&E)

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Lymphoepithelioma-like
gastric carcinoma

Positive staining - normal
  • Hematopoietic cells, including basophils, granulocytes, lymphocytes, macrophages / histiocytes, mast cells, monocytes and plasma cells; NOT mature red blood cells and their immediate progenitors, platelets or megakaryocytes
  • Dendritic cells, fibrocytes (J Immunol 1998;160:419) and medullary thymocytes
Positive staining - disease
Negative staining
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