In addition to the protective function of CD8+ T cells in viral infections and tumors, evidence primarily from studies in the experimental autoimmune encephalomyelitis (EAE), multiple sclerosis (MS), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), rheumatoid arthritis (RA), and vitiigo have been manifested CD8+ T cells play an essential part in the progression of cell and tissue-specific autoimmune disease (13). The gene discussed is CD8A; the disease is type 1 diabetes mellitus.