Evidence for a novel polymorphism affecting both N-linked glycosylation and ligand binding of the IgG receptor IIIB (CD16).

Immunoglobulin G Fc receptor IIIb (FcgammaRIIIb) is constitutively expressed on neutrophils, and has three allelic forms: FcgammaRIIIb-NA1, FcgammaRIIIb-NA2, and FcgammaRIIIb-SH. We identified two Japanese subjects in whom an A to G substitution at nt 221 changes asparagine (N) to serine (S) at amino acid position 45 in the FcgammaRIIIb-NA2 gene. FcgammaRIIIb-NA2-specific monoclonal antibodies (GRM1 and PEN1) did not bind to mutant neutrophils, which lack an N-linked glycosylation site. Furthermore, IgG3-mediated neutrophil phagocytosis by mutant was slightly increased as compared to wild-type donors (Note).