STIM1 is essential for Fc{γ}receptor activation and autoimmune inflammation

Abstract

Fcγreceptors (FcγRs) on mononuclear phagocytes trigger autoantibody and immune complex-induced diseases through coupling the self-reactive immunoglobulin G (IgG) response to innate effector pathways, such as phagocytosis, and the recruitment of inflammatory cells. FcRγ based activation is critical in the pathogenesis of these diseases, although the contribution of FcγR-mediated calcium signaling in autoimmune injury is unclear. Here we show that macrophages lacking the endoplasmic reticulum-resident calcium sensor, STIM1, cannot activate FcγR-induced Ca2+ entry and phagocytosis. As a direct consequence, STIM1 deficiency results in resistance to experimental immune thrombocytopenia and anaphylaxis, autoimmune hemolytic anemia, and acute pneumonitis. These results establish STIM1 as a novel and essential component of FcγR activation and also indicate that inhibition of STIM1-dependent signaling might become a new strategy to prevent or treat IgGdependent immunologic diseases.© 2009 by The American Society of Hematology.