IL21 and atherosclerosis: Since low Blimp1 expression, accompanied by Bcl6, PD1 (Fig. 1g and Supplementary Fig. 2) and IL-21 expression, are defining features of T follicular helper cells (Tfh)25, thus these results indicates that a portion of exTreg cells (RFP+YFP−) are converting to Tfh and Th-1 cells during atherosclerosis development.