However, prior to embarking on large proof-of-concept trials in T1D it is essential that the optimal doses of IL-2 that induce increases in Treg functions are determined while simultaneously defining the cellular outcomes of treatment by detailed immunophenotypic, genetic and epigenetic analysis of peripheral blood cell subsets from participants before, during and after IL-2 in order to define mechanisms and biomarkers. The gene discussed is IL2; the disease is type 1 diabetes mellitus.