We identified two molecules, Fasand Egr2, that are required forTGF-β3 secretion inLAG3+ Treg.Egr2 deficiency in T cellsand B cells results in a lupus-like syndrome, and Egr2 directly activates p21cip1 expression inCD44high Tcells and is involved in the control of Th1 and Th17 differentiation11. Here, IGKV4-1 is linked to drug-induced lupus erythematosus.