CD Markers

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

Revised: 31 December 2015, last major update October 2013

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

PubMed Search: CD45[title]

Related topics: CD45RO, CD45RA, CD45RB, CD45RC

Cite this page: CD45. website. Accessed February 20th, 2018.
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)
  • 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

Images hosted on Pathout server:

Nodular lymphocyte predominant
Hodgkin lymphoma

Left: leukemia cutis; right: myeloid sarcoma of fibula

Images hosted on other servers:


Liver: Kupffer cells,
lymphocytes (fig 2A)

Small intestine

Splenic lymphocytes

Left: thymus; right: tonsil


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)


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)