CD16

CD16a

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

Receptor for the Fc portion of IgG; binds various IgG molecules, including rheumatoid factor

Mediates antibody dependent cytotoxicity of foreign cells, phagocytosis and other antibody-dependent responses; also platelet satellitism (AJCP 1995;103:740)

Affinity to ligand is regulated by glycosylation (Immunology 2003;110:335)

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)

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)

If target cell has class I MHC, then NK cell's killer cell inhibitory receptor (KIR) inhibits cytolysis

Note: preincubation with CD16/CD32 antibodies is commonly used to prevent nonspecific binding

Uses: NK cell and macrophage marker; to subtype leukemia/lymphoma

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

Positive staining (normal): NK cells (10-20%), granulocytes, macrophages, T cells (reactive), immature thymocytes, placental trophoblast

Positive staining (disease): NK proliferative disorders, T cell large granular lymphocyte leukemia, hepatosplenic gamma-delta T cell lymphoma

References: OMIM 146740



CD16b

Also known as Fc gamma receptor III B, low affinity immunoglobulin gamma Fc region receptor III-B

Highly homologous to CD16a

The most common receptor for the Fc domain of IgG on leukocytes

The only Fc receptor linked to the plasma membrane by a GPI (glycosylphosphatidylinositol) anchor

Bears allotypes that define the human neutrophil antigen-1 (HNA-1 and NA) system involved in major post-transfusional reactions (Tissue Antigens 2004;64:119)

Low copy number is associated with glomerulonephritis in systemic lupus erythematosus (Nature 2006;439:851)

CD16+ eosinophils are upregulated in allergic conditions (J Allergy Clin Immunol 2002;109:463)

Affinity to ligand is regulated by glycosylation (Immunology 2003;110:335)

Uses: no significant clinical use by pathologists

Positive staining: neutrophils