FcγRIII (CD16) on human macrophages is a functional product of the FcγRIII‐2 gene

Abstract

The low-affinity Fc receptor for immune-complexed IgG (FcγRIII; CD16) present on in vitro cultured human monocytes are encoded by an FcγRIII-2 gene that, by cDNA sequence analysis, is identical to that expressed on tissue macrophages and on natural killer cells. In macrophages, FcγRIII-2 encodes a glycoprotein of 52-62 kDa, with a peptide backbone of 33 kDa identical to that of the homologous receptor on natural killer cells. Like this and unlike in polymorphonuclear neutrophils, FcγRIII (CD16) on cultured monocytes is insensitive to phosphatidylinositol-specific phospholipase C, is not allelic for the neutrophil NA alloantigens NA-1/NA-2, is not recognized by a monoclonal antibody (1D3) detecting an epitope present only on neutrophil FcγRIII (CD16) and functions to trigger cytotoxicity upon ligand binding.