ObjectiveTo investigate the influence of programmed cell death protein-1 (PD-1) monoclonal antibody on the anti-lung cancer effect of cytokine-induced killer cells (CIK) which were programmed in vitro. MethodsPeripheral blood mononuclear cells from 20 patients (8 males and 12 females with an average age of 56.45±5.89 years ranging from 42 to 65 years) diagnosed with advanced lung cancer from January to May 2019 at the Department of Oncology of Dalian Central Hospital were collected and induced to amplify into CIK cells in vitro. PD-1 monoclonal antibody combined with CIK cell culture group, individual cell culture group and PD-1 monoclonal antibody group were set up to detect the cell killing activity of CIK cells against lung cancer under different effective target ratio conditions, and the ratio of perforin and granzyme positive expression in PD-1 monoclonal antibody combined CIK cell culture group and individual CIK cell culture group was detected by flow cytometry. ELISA method was used to detect the interleukin-2 (IL-2), interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) cytokine secretion levels in the two groups.ResultsThe killing effect of CIK cells on A549 lung cancer cells increased with the increase of effective target ratio by CCK8, and PD-1 monoclonal antibody increased the killing effect of CIK cells on A549 lung cancer cells under different effective target ratio, E∶T=5∶1 (28.5%±1.9% vs. 20.3%±1.8%), 10∶1 (40.6%±2.4% vs. 31.7%±2.1%), 20∶1 (57.4%±3.5% vs. 44.7%±3.8%), 40∶1 (74.1%±8.3% vs. 60.8%±5.3%). The killing effect of PD-1 monoclonal antibody combined with CIK cells and CIK cells alone on A549 lung cancer cells was statistically different (P<0.05). The killing effect of cells in both groups on lung cancer A549 cells was stronger than that of the PD-1 monoclonal antibody group (P<0.01). The results of flow cytometry showed that PD-1 monoclonal antibody increased the positive ratio of perforin and granzyme release in CIK cells, and the positive ratios of perforin release (46.7%±3.5%% vs. 35.1%±2.2%) and granzyme release (34.6%±3.8% vs. 25.7%±3.3%) in PD-1 monoclonal antibody combination with CIK cells group and CIK cells group were statistically different (P<0.05). Similarly, the secretion levels of IL-2, TNF-α, and IFN-γ cytokines were also increased in the PD-1 monoclonal antibody combined with CIK cells group compared with the CIK group (5 409.0±168.8 pg/mL vs. 4 300.0±132.3 pg/mL, 252.7±16.7 pg/mL vs. 172.5±8.6 pg/mL, 327.2±23.5 pg/mL vs. 209.7±16.0 pg/mL, P<0.05).ConclusionPD-1 monoclonal antibody can promote the release of tumoricidal substances in CIK cells and improve the killing effect of CIK cells on lung cancer A549 cells. It is speculated that the infusion of PD-1 monoclonal antibody before CIK cell adoption in lung cancer patients may be more beneficial to the treatment of disease. PD-1 monoclonal antibody combined with CIK cell therapy is promising as a new type of lung cancer immunotherapy.