CD Markers - CD16a

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CD Markers

CD16a

Reviewers: Nat Pernick, M.D., (see Reviewers page)
Revised: 8 February 2011, last major update January 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

General
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● Receptor for the Fc portion of IgG

Terminology
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● Also known as Fc gamma receptor III A, FCGR3A, low affinity immunoglobulin gamma Fc region receptor III-A

Physiology
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● Gene is similar to that for CD16b
● Binds various IgG molecules, including rheumatoid factor
● Mediates antibody dependent cytotoxicity of foreign cells, phagocytosis and other antibody-dependent responses, but if target cell has class I MHC, the NK cell's killer cell inhibitory receptor (KIR) inhibits cytolysis
● Mediates platelet satellitism (Am J Clin Path 1995;103:740)
● Affinity to ligand is regulated by glycosylation (Immunology 2003;110:335)

Clinical features
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● CD14+ CD16+ monocytes have increased capacity to produce proinflammatory cytokines such as TNF-alpha, and are elevated in various inflammatory diseases, including coronary artery disease (Thromb Haemost 2004;92:419)
● CD16a polymorphisms influence: (a) the severity but not the incidence of IgA nephropathy in Japanese patients (Nephrol Dial Transplant 2005;20:2439); (b) pathogenesis of coronary artery disease (Atherosclerosis 2005;180:277); (c) clinical response to rituximab (Cancer Res 2004;64:4664)
● Loss of CD16a in children is associated with recurrent viral infections

Uses
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● NK cell and macrophage marker
● Used to subtype leukemia/lymphomas
● Note: preincubation with CD16/CD32 antibodies is commonly used to prevent nonspecific binding

Diagrams
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NK cell mediated cytotoxicity [CD16 / FcgammaRIII is THE activating receptor on NK cellS]

Positive stains - normal
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● NK cells, granulocytes, macrophages, eosinophils, T cells (reactive), immature thymocytes, placental trophoblast

Positive stains - disease
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● NK proliferative disorders, hepatosplenic alpha-beta and gamma-delta T cell lymphomas (variable), T cell large granular lymphocyte leukemia (variable)

Negative stains
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● Basophils; NK / T cell lymphoma nasal type

Additional references
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● MIM 146740

End of CD Markers > CD16a

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