Fc gamma RIIIB / CD16b (NA2)

CD16 is a low affinity Fc receptor, and has been identified as Fc receptors FcγRIIIa (CD16a) and FcγRIIIb (CD16b). These receptors bind to the Fc portion of IgG antibodies. CD16 encoded by two different highly homologous genes in a cell type-specific manner.CD16 is found on the surface of natural killer cells, neutrophil polymorphonuclear leukocytes, monocytes and macrophages. CD16B is also kown as FCGR3B and FCG3B, is expressed specifically by polymorphonuclear leukocytes (neutrophils) and stimulated eosinophils. CD16B is the low affinity receptor for the Fc region of immunoglobulins gamma. FCGR3B binds complexed or aggregated IgG and also monomeric IgG. Contrary to III-A, FCG3B is not capable to mediate antibody-dependent cytotoxicity and phagocytosis. CD16B may serve as a trap for immune complexes in the peripheral circulation which does not activate neutrophils.