Fc gamma receptors (FccRs) mediate a variety of immune responses after binding to IgG-opsonized pathogens or immune complexes, and therefore act as immune regulators in both autoimmune and infectious diseases [5] [6] [7] [8] [9] . According to their affinity to IgG, FccRs are categorized into high-affinity and lowaffinity receptors. FccRI is the only known high-affinity receptor.