Co-transfer of CD4+ and CD8+ T cells from NOD mice into Rag1−/− NOD mice upregulated the incidence of diabetes, whereas co-transfer of CD4+ and CD8+ T cells from IL-27rα−/− NOD mice into Rag1−/− NOD mice did not induce diabetes, demonstrating that IL-27 signaling is essential for T1D development (191). The gene discussed is CD8A; the disease is type 1 diabetes mellitus.