Recent studies have shown that mice with PD-1 deficiencies develop several autoimmune diseases, including lupus-like disease, autoimmune dilated cardiomyopathy, and diabetes, suggesting that the PD-1/PD-L1 pathway could also be targeted with agonists for treating autoimmune diseases (3, 4, 5). The gene discussed is PDCD1; the disease is autoimmune disease.