The FcγRIIb‐specific nature of IgG4‐L235E has utility for mAb‐mediated immune agonism therapies that are dependent on FcγRIIb interaction and of anti‐inflammatory mAbs in allergy and autoimmunity that harness FcγRIIb inhibitory signaling. The gene discussed is FCGR2B; the disease is allergic disease.