We have demonstrated that transgenic expression of PD-L1 (ligand of PD-1) [23] or a membrane-bound, agonistic single-chain anti-CTLA-4 Fv antibody (anti-CTLA-4 scFv) [24] on islets in NOD mice reduces the severity of insulitis and suppresses the development of diabetes. This evidence concerns the gene CD274 and diabetes mellitus.