Anti-FcγRIIB mAb suppresses murine IgG-dependent anaphylaxis by Fc domain targeting of FcγRIII

Cross-linking FcγRIIB to stimulatory FcγRs through the Fc domains of an anti-FcγRIIB mAb induces and then suppresses IgG-mediated anaphylaxis without affecting IgE-mediated anaphylaxis. Because IgG- and IgE-mediated anaphylaxis can be mediated by the same cell types, this suggests that desensitization acts at the receptor rather than cellular level. Sequential treatment with the F(ab′)2 fragment of anti-FcγRIIB mAb followed by intact anti-FcγRIIB safely prevents IgG-mediated anaphylaxis.