Thus, together with the improved function of the B6 over the NOD Cd101 allele the increased T1D frequency in CD101−/− NOD.B6 Idd10 and CD101−/− NOD.B6 Idd10/18 mice as compared to their CD101+/+ counterparts is associated with a reduction of Tregs in pancreatic lymph nodes suggesting that CD101 acts locally at the site of T cell priming. This evidence concerns the gene CD101 and type 1 diabetes mellitus.