After we found the optimal in vitro conditions using cells isolated from human leukopacks (enriched leukocytes from whole blood) obtained from anonymous donors, we performed a study involving T1D-related subject groups to test the hypothesis that Tregs cannot suppress two different responder T cell subsets equally well (CD4+CD25- and CD4+CD25low). This evidence concerns the gene IL2RA and type 1 diabetes mellitus.