CD16a with oligomannose-type N-glycans is the only “low-affinity” Fc γ receptor that binds the IgG crystallizable fragment with high affinity in vitro

-glycan composition, including CD16b, which differs from CD16a by only four amino acid residues. This result indicates that CD16a is unique among the low-affinity FcγRs, and modifying only the glycan composition of both the IgG1 Fc ligand and receptor provides a 400-fold range in affinities.