FcγR‐mediated mechanism of action Effector responses Action Dominant receptor Activation Antibody‐dependent cell‐mediated cytotoxicity Direct killing of target cell FcγRIIIa Antibody‐dependent cell‐mediated phagocytosis, trogocytosis Direct killing of target cell FcγRIIIa, FcγRIIa, FcγRI Antigen presentation Vaccine‐like immunity post‐mAb therapy FcγRIIa, FcγRI, FcγRIIIa Inhibition Reduce B‐cell proliferation or innate cell activation by antibody complexes Inhibition of ITAM cell activation (i.e. BCR) or activating‐type FcR (i.e. FcγR, FcεRI, FcαRI). Note that the FcγRIIb must be co‐cross‐linked with the ITAM activating receptor. FcγRIIb Sweeping Internalization Removal of small immune complexes FcγRIIb a Scaffolding Target agonism or apoptosis Passive “super‐cross‐linking” of mAb on opsonized target cell, for example, CD40, CD28, CD20, by FcγR on an adjacent cell FcγRIIb; also FcγRIIa, FcγRI?