Abstract:

Objective To examine the influence of cisplatin（DDP） on the expression of programmed cell death ligand-1（PD-L1） and functions of lymphocytes in the established microimmune environment of lung squamous cell cancer. Methods Flow cytometry was used to analyze the influence of DDP（0， 0.5， 1.0， 2， 4， 8 mg／L） on the surface expression of PD-L1 in cell line of NCI-H520 cells. The lymphocytes were cocultured with cancer cells in the presence of DDP（1.0 mg／L）. Cells of different coculture systems were divided into six groups： T- represented the group of lymphocytes untreated by DDP； T+ represented the group of lymphocytes pretreated by DDP； T-H- represented the group of co-culturing of lymphocytes and NCI-H520 cells untreated by DDP； T-H+ represented the group of co-culturing of DDP untreated lymphocytes and DDP pretreated NCI-H520 cells；T+H- represented the group of co-culturing of DDP pretreated lymphocytes and DDP untreated NCI-H520 cell； T+H+ represented the group of co-culturing of lymphocytes and NCI-H520 cell pretreated by DDP. The apoptotic rates between lymphocytes（CD4+ and CD8+ T lymphocytes） and IFN-γ production were assessed by flow cytometry and ELISA from different co-culture systems， respectively. Results DDP inhibited the growth of NCI-H520 cells in a concentration-dependent pattern. PD-L1 expression was up-regulated in the DDP-treated NCI-H520 cell lines compared with the untreated group（P＜0.05）. In the microimmune environment established by NCI-H520 and activated lymphocytes， PD-1+T cells were more susceptible to apoptosis than PD-1-T cells in both the subgroups of CD4+ and CD8+ T lymphocytes（P＜0.05）. The apoptotic rates of the CD4+ and CD8+ T lymphocytes co-cultured with DDP pretreated NCI-H520 cells were significantly higher and the IFN-γ production was significantly lesser than those co-cultured with DDP untreated NCI-H520 cells（P＜0.05）. Conclusion DDP inhibited the immune microimmune environment of lung squamous cell cancer by up-regulating the expression of PD-L1 possibly， providing theoretical basis for association of PD-L1 antibody and DDP involved chemotherapy.