Numerous studies have been reported that PD-1 and PD-L1 play an important role in the pathogenesis of autoimmune diseases in PD-1-deficient murine models, which present lupus-like glomerulonephritis, arthritis, and fatal autoimmune dilated cardiomyopathy [9–11]. This evidence concerns the gene PDCD1 and systemic lupus erythematosus.