According to the hypothesis that IFN-γ could impact the hepatic CD8+ T and NK cell phenotype and has a role in PBC pathogenesis, the complete absence of IFN-γ in Mdr2−/−x Ifng−/− mice resulted in a reduction in NK cell and CD8+ T cell frequencies expressing the cytotoxic effector molecules of granzyme B and TNF-related apoptosis-inducing ligand (TRAIL) attenuating liver fibrosis. The gene discussed is CD8A; the disease is primary biliary cholangitis.