[Effect of cisplatin alone or combined with monoclonal anti-programmed death ligand-1 antibody on lung adenocarcinoma cell line SPCA-1 and T lymphocytes].

OBJECTIVE: To observe the effect of cisplatin alone or combined with anti-programmed death ligand 1 monoclonal antibody (anti-PD-L1 mAb) on the co-culture system of lung adenocarcinoma SPCA-1 cells and T lymphocytes, and therefore to study the immunotherapeutic effect of anti-PD-L1 mAb on lung cancer. METHODS: Human adenocarcinoma SPCA-1 cell line was selected by flow cytometry (FCM) due to its high expression of membranous programmed death ligand-1 (PD-L1). The concentration of cisplatin was determined by CCK-8 method depending on the inhibition rate of SPCA-1 cell, which was set to less-than-or-equal-to 20% (IC20). After treatment with different concentrations of cisplatin, cell proliferation (A value) of SPCA-1 cells and T lymphocytes were detected by CCK-8 method and cell cycle of SPCA-1 cells and cell apoptosis of T lymphocytes were analyzed using PI staining. Treated with different concentrations of cisplatin alone or in combination with anti-PD-L1, T lymphocyte proliferation in co-culture system was determined by CCK-8 method, and cytokines such as IFN (interferon)-γ, IL-2, IL-10 and TNF-α were detected with enzyme linked immunosorbent assay (ELISA) method. RESULTS: The IC20 of cisplatin on SPCA-1 cells was ≤ 0.78 mg/L. The proliferation of SPCA-1 cells were inhibited with different concentrations of cisplatin in a concentration-dependent manner (0.78∼12.5 mg/L) (P < 0.001). Compared with the group treated with high-dose of cisplatin (12.5 mg/L), the proliferation of T lymphocytes treated with low-dose of cisplatin (0.78 mg/L) was higher (t = 3.508, P < 0.05) and the number of late apoptotic and dead T lymphocytes in the co-culture system was reduced (t = 17.55, P < 0.001). Compared with the group of co-culture system, cisplatin (0.78 mg/L) combined with anti-PD-L1 (1.5 mg/L) significantly enhanced the proliferation of T lymphocytes in the co-culture system (t = 4.419, P < 0.01). Also, the levels of T helper cell type-1 (Th1) cytokines such as IFN-γ, IL-2 and TNF-α were up-regulated (t = 25.79-55.15, P < 0.01) and the T helper cell type-2 (Th2) cytokine IL-10 was down-regulated (t = 18.38, P < 0.01). CONCLUSION: Low-dose of cisplatin combined with anti-PD-L1 could effectively promote the proliferation of T lymphocytes in the microenvironment and increase the secretion of Th1 type cytokines. This may reduce the toxic effect of high-dose antineoplastic agents on immune cells and help eradication of tumor cells.