Regarding T1D, suppressive CD8+ subsets were indeed able to prevent and even reverse T1D in non-obese diabetic (NOD) mice [15] where, in particular, the subset of CD8+PD-1+ Tregs, expressing the β subunit of IL-2 receptor CD122 instead of CD25, revealed to be functional in ameliorating disease [16]. Here, PDCD1 is linked to type 1 diabetes mellitus.