Since we previously showed that increases in ANA+ IgG PCs in patients with SLE and lupus-prone mice occur through aberrant IgG PC differentiation rather than as a result of an antigen-specific tolerance defect (31), we also analyzed tolerance checkpoints for ANA+ B cells and PCs in Fcgr2b-cKO mice. Here, FCGR2B is linked to systemic lupus erythematosus.