Human FcgRIIa mediates attenuation of IFN-I response in human monocytes

It is generally believed that there is continued cross-regulation between adaptive humoral immunity and Type I interferon (IFN-I) response during viral infections, but the question how antibodies (Abs), and/or Ab-antigen immunocomplexes (ICs), regulate IFN-I production and/or signaling in immune cells remains unanswered. Here we report that plate-coated IgG (cIgG), a mimic IC without antigen restriction, could dampen IFN-I signaling in monocytes through FcgRIIa. Overall design: Freshly isolated CD14+ monocytes from peripheral blood of 3 unrelated healthy donors were cultured for 24 hrs in RPMI-10 medium or IVIG(10 µg/ml) for preparation, then half of these cultures were washed and given a 12 hrs IFN-alpha or IFN-beta (10 ng/mL) stimulation,respectively.