Thus, B‐cell activation by the binding of the antigen in the immune complex to the BCR is regulated by the simultaneous binding of the Fcs of the immune complex to FcγRIIb1 on the same cell. In innate leukocytes, the activating‐type FcR (i.e. FcγRI, FcγRIIa, FcγRIIc, FcγRIII) and the high‐affinity IgE receptor, FcεRI, and the IgA receptor, FcαRI, are all modulated by immune complex co‐engagement with FcγRIIb2.