CD4 and Autoimmunity: As predicted from the first model, Il2ramut/mut Treg cells fail to suppress autoreactive Tconv cell-mediated autoimmunity with a rapid loss of weight and massive infiltrates of T cells in multiple organs (lung, liver, small intestine) in contrast to control groups transferred with WT Treg cells or only CD4+ Tconv cells (Fig. 7c and Supplementary Fig. 7c).