Higher serum AEA levels correlated with worse OS in cancer patients; in mice THC and AEA significantly inhibited CD8+ T cell proliferation, TNF-α and IFN-γ expression, accelerated tumor growth and diminished effects of anti-PD 1.Ablation of CB2 promoted T cell proliferation without any effect on their negative selection; Tumors showed slower growth and better survival in CB2 KO mice; TILs were more activated with less exhaustion markers. The gene discussed is CD8A; the disease is cancer.