Figure 2.

Afucosylation of antigen-specific IgG can affect steady-state FcγRIII occupancy and effector activities in humans.

Under steady-state conditions (left panel), most FcγRIII are occupied by afucosylated IgGs with random specificities (depicted in green, ~6% of total plasma IgG) as their affinity is higher than their fucosylated counterparts (depicted in gray, ~94% of total plasma IgG) [48,58]. During effector responses (right panel), fucosylated IgG (in blue) displaces an aspecific afucosylated IgG already occupying FcγRIII less efficiently, due to differences in affinities [48]. By contrast, afucosylated IgG response (in orange) will displace an aspecific afucosylated IgG more easily, resulting in strong antibody-dependent cellular cytotoxicity and phagocytosis (ADCC/ADCP) activity [48]. Abbreviations: ADCC, antibody-dependent cellular cytotoxicity; ADCP, antibody-dependent cellular phagocytosis; NK, natural killer.