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

Abstract

Autoantibodies induce various autoimmune diseases, including systemic lupus erythematosus (SLE). We previously described that CD4 + CD25-LAG3 + regulatory T cells (LAG3 + Treg) are regulated by Egr2, a zinc-finger transcription factor required for the induction of T-cell anergy. We herein demonstrate that LAG3 + Treg produce high amounts of TGF-β3 in an Egr2- and Fas-dependent manner. LAG3 + Treg require TGF-β3 to suppress B-cell responses in a murine model of lupus. Moreover, TGF-β3- and LAG3 + Treg-mediated suppression requires PD-1 expression on B cells. We also show that TGF-β3-expressing human LAG3 + Treg suppress antibody production and that SLE patients exhibit decreased frequencies of LAG3 + Treg. These results clarify the mechanism of B-cell regulation and suggest therapeutic strategies.