Abstract: ObjectiveTo study the cytotoxic effect of Cisplatin pretreated on cytokine-induced killer (CIK) against lung cancer cells. MethodsLung cancer cell line A549 and H446 were used in the present study. CFSE/PI double labeling method was used to detect the cytotoxic effect of CIK after Cisplatin pretreatment lung cancer cell line A549 and H446 at different concentration, different time and different CIK effect/target ratios. ResultsWe succeed cultivate CIK as effect cells. With the increase of DDP precondition concentration, the cytotoxic effect of CIK increased. With the prolong of DDP precondition time, the cytotoxic effect of CIK increased, and after DDP precondition target cells 18 h at the concentration of 25 ng/ml, it has no significant difference on target cells, but with the effect/target ratio increase, the cytotoxic effect of CIK increased significantly compared to the without DDP precondition one. ConclusionPreconditioning lung cancer cell with Cisplatin can enhance the cytotoxic effect of CIK. This study might provide valuable information on the clinical application of CIK cells.