We previously showed that injection of pCI/ppins but not pCI/ppinsΔA12-21 DNA into H-2b PD-1- or PD-L1-deficient mice induced CD8+ T cell-mediated autoimmune diabetes (Figures S1B and S1C).7, 8 However, the failure to induce CD8+ T cells in PD-1−/− and PD-L1−/− mice by pCI/ppinsΔA12-21 facilitated the induction of a systemic Foxp3+CD25+CD4+ Treg cell immunity that suppressed diabetes development by de novo primed Kb/A12-21-specific CD8+ T cells.18 This evidence concerns the gene CD4 and diabetes mellitus.