Fc receptors in immune thrombocytopenias: a target for immunomodulation?

In autoimmune disease, Fc receptors (FcRs) form the interface between immune effector cells and their antibody-coated targets, and as such are attractive targets for immunomodulatory therapy. In this issue of the JCI, two highly novel studies of Fc-FcR interactions provide new insights into the role of FcRs in immune thrombocytopenia. Asahi et al. utilized a comprehensive platform of immunological assays to examine the mechanism underlying Helicobacter pylori-associated immune thrombocytopenic purpura, and Ghevaert et al. describe a specially designed antibody that saturates binding sites on fetal platelets without initiating FcgammaR-mediated platelet phagocytosis, preventing the binding of pathological maternal anti-HLA antibodies that cause fetomaternal alloimmune thrombocytopenia (see the related articles beginning on pages 2939 and 2929, respectively). These reports illustrate how a remarkably detailed molecular understanding of the FcR network may translate into new therapeutic strategies with high clinical impact.