In keeping with these findings, a higher number of activated hepatic CD8+ T cells which express effector cytokines (IFN-γ, TNF-a) together with both progressive liver damage and HCC incidence were observed in Pdcd1−/− mice suggesting the unfavorable effects of anti-PD-1 treatment in NASH which support the tissue-damage role exerted from CD8+PD-1+ T lymphocytes. This evidence concerns the gene PDCD1 and metabolic dysfunction-associated steatohepatitis.