The increase in IRF5 expression after activation with anti-IgM, anti-CD40, and R848 in vitro suggested the possibility that IRF5 might be increased in GC B cells in FcγRIIB−/−Yaa mice in vivo, because TLR7 activation is thought to be important for spontaneous GC formation in other lupus models (50). This evidence concerns the gene CD40LG and systemic lupus erythematosus.