BCR and Autoimmunity: Although antibody-mediated crosslinking of the BCR precludes IL-10 production upon simultaneous stimulation with LPS or CD40 ligation in B cells from naïve mice (29, 31, 42, 94) or human blood (30, 103), Bregs from mice with induced autoimmunity are able to secrete IL-10 when challenged with cognate antigens, or BCR crosslinking antibodies, plus CD40 ligation (3, 10, 25).