Published online Nov 28, 2008. doi: 10.3748/wjg.14.6853
Revised: November 4, 2008
Accepted: November 11, 2008
Published online: November 28, 2008
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 culture supernatant were 202.9 ± 53.0 pg/mL, 88.6 ± 4.6 pg/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 < 0.05). The OD value for MTT assay in the blocking group (0.29 ± 0.06) was significantly higher than that (0.19 ± 0.09) in the control group (P < 0.05).
CONCLUSION: PD-1 expression on Jurkat cells is up-regulated by hepatoma cells, cytokines and cytotoxic action are elevated after PD-1/PD-L1 is blocked.