欧美国产日韩在线免费观看-欧美日韩成人激情一区二区-欧美久久综合一区二区-亚洲av寂寞少妇久久

CD16 is known as low affinity IgG receptor III （FcγRIII）. It is expressed as two distinct forms （CD16a and CD16b）. CD16a （FcγRIIIA） is a 50-65 kD polypeptide-anchored transmembrane protein. It is expressed on the surface of NK cells, activated monocytes, macrophages, and placental trophoblasts in humans. CD16b （FcγRIIIB） is a 48 kD glycosylphosphatidylinositol （GPI）-anchored protein. Its extracellular domain is over 95% homologous to that of CD16a, and it is expressed specifically on neutrophils. CD16 binds aggregated IgG or IgG-antigen complex which functions in NK cell activation, phagocytosis, and antibody-dependent cell-mediated cytotoxicity （ADCC）.