CD Markers
CD45

Author: Nat Pernick, M.D. (see Authors page)

Revised: 31 December 2015, last major update October 2013

Copyright: (c) 2003-2015, PathologyOutlines.com, Inc.

PubMed Search: CD45[title]

Related topics: CD45RO, CD45RA, CD45RB, CD45RC

Cite this page: CD45. PathologyOutlines.com website. http://pathologyoutlines.com/topic/cdmarkerscd45.html. Accessed December 8th, 2016.
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
Micro Images

Images hosted on Pathout server:

Nodular lymphocyte predominant
Hodgkin lymphoma


Left: leukemia cutis; right: myeloid sarcoma of fibula



Images hosted on other servers:

Normal-

Liver: Kupffer cells,
lymphocytes (fig 2A)

Small intestine

Splenic lymphocytes


Left: thymus; right: tonsil



Lymphoma-

Immunoreactivity of the lymphoma cells for cytokeratin (A) and CD20 (C) but not CD45 (B)


Left: B cell lymphoma-unusual CD45- case (fig B); right: CLL (fig 3a)


Left: diffuse large B cell lymphoma-urine cytology; middle: diffuse large B cell lymphoma-H&E (fig 7); right: Hodgkin’s-Reed-Sternberg cells are CD45- (fig 3C)



Other-

Histiocytic sarcoma (fig C)


Leukemic vasculitis in the context of leukemia cutis,in a patient with atypical chronic myeloid leukemia


Lymphoepithelioma-like carcinomas: tumor cells are CD45-, but infiltrating lymphocytes are CD45+
(left: stomach; right: cervix)



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
Flow Cytometry Description

Images hosted on other servers:

Anaplastic large cell lymphoma


Transient myeloproliferative disorder
with erythroid differentiation in
Down’s syndrome (figure C)