In PD-L1-deficient mice, CD8+ T cells spontaneously accumulate in the liver, accelerating hepatocyte damage in an experimental model of autoimmune hepatitis (64), whereas antigen-specific CD8+ T cell responses and cytotoxic T lymphocyte activity are diminished in PD-L2-deficient mice (65). The gene discussed is PDCD1LG2; the disease is autoimmune hepatitis.