Involvement of Fcα/μR (CD351) in autoantibody production

Antibody exerts various immune responses via binding to Fc receptors expressed on immune cells. Although several reports have demonstrated that IgM prevents autoantibody production, the role of IgM Fc receptors is largely unknown. To analyze the involvement of Fc alpha/mu R (CD351), an Fc receptor for IgM and IgA expressed on B cells and follicular dendritic cells (FDCs), in IgM-mediated suppression of autoantibody production, we generated mice deficient in Fc alpha/mu R on the background of MRL/MpJ-Fas(lpr/lpr) (Fcamr(-vertical bar-)Fas(lpr/lpr) mice. Fcamr(-vertical bar-)Fas(lpr/lpr) mice showed significantly lower titers of IgG autoantibodies against double strand (ds) DNA, histone and cardiolipin in the sera than did Fcamr+/+Fas(lpr/lpr) mice. Moreover, Fcamr(-vertical bar-)Fas(lpr/lpr) mice showed higher survival rate at the ages of 28, 32 and 40 weeks old, compared with Fcamr(+/+)Fas(lpr/lpr) mice. These results suggest that Fc alpha/mu R enhances, rather than suppresses, autoantibody production. (C) 2013 Elsevier Ltd. All rights reserved.