TGF-β3-expressing CD4 + CD25 − LAG3 + regulatory T cells control humoral immune responses

B cells reactive against self antigens can cause autoimmune disease, but are normally suppressed by regulatory T cells (Tregs). Here the authors show that a subset of Tregs can suppress lupus in a mouse model by making TGF-β3 cytokine and by engaging an inhibitory PD-1 receptor on B cells.