AIM: To investigate the effect of hepatoma cells on up-regulation of programmed cell death-1 (PD-1), and the function of PD-1 on T cells.METHODS: HepG2 or HepG2.2.1.5 cells were co-cultured with a lymphoma cell line-Jurkat cells. PD-1 expression was detected by flow cytometry. IL-2, INF-γ and IL-10 in culture supernatant were detected by enzyme-linked immunosorbent assay (ELISA). Cytotoxic action of T cells was determined by MTT reduction assay-direct mononuclear cell cytotoxicity assay.RESULTS: The PD-1 expression on Jurkat cells increased by 16.17%±2.5% and 17.43%±2.2% after HepG2 or HepG2.2.1.5 cells were co-cultured for 48 h. The levels of IL-2, INF-γ and IL-10 in the culturesupernatant were 202.9±53.0 pg/mL, 88.6±4.6pg/mL and 63.7±13.4 pg/mL respectively, which were significantly higher than those (102.9±53 pg/mL, 39.3±4.2 pg/mL, and 34.6±13.7 pg/mL) in the control group (P