Marker for NK cells, monocytes and macrophages, and neutrophils. Monoclonal antibody c127 recognizes CD16, the low affinity receptor for IgG (Fc?RIII). CD16 is expressed on the majority of NK cells, on granulocytes, monocytes and macrophages, and on a subset of T cells. CD16 is involved in antibody-dependent cellular cytotoxicity (ADCC). This molecule is encoded by Fc?RIII-A or Fc?RIII-B genes. The genetic heterogeneity of Fc?RIII generates alternative membrane-anchored proteins with distinct signaling capacities when cross-linked by immune complexes. CD16 exists in two distinct forms, as a a single-pass type I integral membrane protein (CD16a), and as a glycosyl phosphatidyl inositol (GPI) form (CD16b). In humans, the transmembrane form is expressed on NK cells and macrophages while the GPI linked form is expressed on granulocytes. Antibody c127 has been described to detect both forms. However, immunohistochemically it reacts mainly with granulocytes. Application: IHC (f), FACS