CD Markers

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CD Markers

CD4

Reviewers: Charanjeet Singh, M.D., University of Minnesota (see Reviewers page)
Revised: 8 February 2011, last major update December 2010
Copyright: (c) 2002-2010, PathologyOutlines.com, Inc.

General
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● Marker of T helper cells, important in T cell activation, receptor for HIV (Wikipedia)

Terminology
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● Also called OKT4

Physiology
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● At #12 pter-p12
● Nonpolymorphous glycoprotein belonging to immunoglobulin superfamily (Cell 1985;42:93)
● Expressed on surface of T helper cells; serves as coreceptor in MHC class II-restricted antigen induced T cell activation
● CD4+ CD25+ T cells maintain peripheral tolerance and prevent autoimmunity (Curr Top Microbiol Immunol 2005;293:115)
● Serves as HIV receptor on T cells, macrophages, brain
● Homologous to CD223

Drawings
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CD4+ T cell and antigen presenting cell

CD4 acting as HIV receptor

Clinical features
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● Downregulated by HIV Nef protein during AIDS progression (J Virol 2003;77:11536, J Biol Chem 2003;278:33912)
● Normally CD4 > CD8; in HIV patients, CD4/CD8 ratio is inverted (i.e. CD4 < CD8) and patients are at risk for opportunistic infections, particularly if CD4 < 200

Interpretation
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● Staining is usually cytoplasmic and has membrane accentuation

Uses
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● Classify lymphomas and inflammatory conditions
● Serum levels are marker of HIV disease progression and response to therapy (CD4+ cells are killed by HIV)
● Serum levels also increased by transient stress (Am J Clin Pathol 2002;117:819)

Positive stains - normal
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● T helper cells, thymocytes (80-90%), granulocytes, macrophages, Langerhans cells, dendritic cells
● Expressed in specific regions of brain

Positive stains - disease
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● Many post-thymic T cell leukemia/lymphomas
● Blastic plasmacytoid dendritic cell neoplasm
● Indolent T cell lymphoblastic proliferations, pyothorax associated lymphoma (some)
● Acute myeloid leukemia (Am J Clin Pathol 1995;104:204), cutaneous lymphomatoid granulomatosis (Am J Surg Pathol 2001;25:1111), florid antiviral inflammatory response (Mod Pathol 2003;16:166), granulomatous eccrinotropic lymphomatoid papulosis (Am J Clin Pathol 2003;119:731), histiocytic lymphoma / sarcoma, Kikuchi-Fujimoto disease (decreased CD4:CD8 ratio in affected areas of lymph node, in contrast to lymphoma, Am J Clin Pathol 2004;122:141), pityriasis lichenoides
● Rarely Burkitt’s lymphoma can show CD4 on flow cytometry (Am J Clin Pathol 2010;134:127)

Negative stains
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● NK cells
● B cell lymphoma (usually), enteropathy associated T cell lymphoma, epidermotropic cutaneous T-cell lymphoma, hepatosplenic alpha/beta and gamma/delta lymphoma, Hodgkin’s lymphoma (usually), T cell lymphoma with cytotoxic phenotype
● Nonhematopoietic neoplasms

Micro images
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Various images

Additional references
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● MIM 186940

End of CD Markers > CD4

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