CD Markers
CD45
Copyright: 2003-2021, PathologyOutlines.com, Inc.
PubMed Search: CD45[title]
Related topics: CD45RO, CD45RA, CD45RB, CD45RC
CD45
Author: Nat Pernick, M.D.
Topic Completed: 1 October 2013
Minor changes: 8 October 2020
Copyright: 2003-2021, PathologyOutlines.com, Inc.
PubMed Search: CD45[title]
Related topics: CD45RO, CD45RA, CD45RB, CD45RC
Table of Contents
Definition / general | Pathophysiology | Clinical features | Uses by pathologists | Microscopic (histologic) images | Positive staining - normal | Positive staining - disease | Negative stainingCite this page: Pernick N. CD45. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cdmarkerscd45.html. Accessed April 15th, 2021.
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
- Confirm presence of inflammatory cells, including intestinal intraepithelial lymphocytes (Arch Pathol Lab Med 2002;126:897)
- Confirm hematopoietic nature of tumors
- May assist in classification of lymphomas and leukemias (Am J Clin Pathol 1998;110:797)
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:
Diffuse large B cell lymphoma (urine cytology)
Diffuse large B cell lymphoma (H&E)
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
- AML (Am J Clin Pathol 1998;109:211), anaplastic large cell lymphoma (usually, Am J Clin Pathol 2003;119:205, Hum Pathol 1990;21:624), B and T cell lymphomas (most), CD4(+) CD56(+) lineage-negative malignancies (Am J Surg Pathol 2005;29:1274) and dendrocytoma (Am J Surg Pathol 1990;14:867)
- Giant cell tumor of tendon sheath (Mod Pathol 1995;8:155), histiocytic sarcoma (Am J Surg Pathol 1998;22:1386), inflammatory pseudotumors (some, Am J Clin Pathol 1996;105:430) and interdigitating dendritic cell sarcoma (variable, Am J Clin Pathol 2001;115:589)
- Leukemia cutis, lymphocyte predominant Hodgkin’s lymphoma (Am J Surg Pathol 1994;18:526), myeloid sarcoma (Am J Surg Pathol 1993;17:1011) and mycobacterial spindle cell pseudotumor in lymph nodes
- Plasma cell neoplasms (variable, Blood Cells Mol Dis 2004;32:293), post-transplant lymphoproliferative disorders (Am J Clin Pathol 2004;121:246), preB lymphoblastic lymphoma (low, Am J Clin Pathol 2009;132:940) and primary effusion lymphoma (Am J Surg Pathol 2004;28:1401)
- Reticulohistiocytoma (variable, Am J Surg Pathol 2006;30:521), transient myeloproliferative disorder of Down's syndrome (Am J Clin Pathol 2001;116:204)
- Candida albicans yeast forms (Am J Clin Pathol 2000;113:59)
- Rarely carcinomas (undifferentiated / neuroendocrine, Mod Pathol 1998;11:1204 or necrotic)
Negative staining
- Red blood cells and their immediate progenitors, megakaryocytes, osteoblasts and platelets
- Epithelial tumors (although necrotic carcinomas may be CD45+, Am J Clin Pathol 1998;110:641), follicular dendritic cell sarcoma (Am J Clin Pathol 1995;103:90), germ cell tumors, melanoma, mesothelioma, multiple myeloma (CD45+ in 9% by flow cytometry, Am J Clin Pathol 2004;121:482, Am J Clin Pathol 2010;133:265) and sarcoma
- Reed-Sternberg cells in classic Hodgkin’s lymphoma (Am J Pathol 1991;139:701)
- Note that infiltrating lymphocytes in any disorder are typically CD45+, and they must be distinguished from tumor cells
