Mice with altered FcγRIIb expression or a B-cell-specific/ubiquitous deletion of FcγRIIb show higher levels of IgM and IgG antibody responses, have an impaired germinal center reaction, and develop a systemic lupus erythematosus (SLE) like disease on susceptible genetic backgrounds (Bolland and Ravetch, 2000; Bolland et al., 2002; Espéli et al., 2012; Li et al., 2014; Su et al., 2004a; Su et al., 2004b; Takai et al., 1996). Here, CD40LG is linked to systemic lupus erythematosus.