In vitro tumor killing effect of CIK cells in cord blood on drug-resistant leukemia cells and its mechanism

Objective:To explore the new strategy of intervening and overcoming multi-drug resistance(MDR)of leukemia cells.Method:The killer cells in cord blood(CB-CIK)were induced by CD3 monoclonal antibody(CD3McAb)combined with multi-cytokines,and subsequently used to kill drug-resistant leukemia cells(K562/A02)in vitro.Cytotoxic effect was detected by MTT colourimetry.Expression of P-glycoprotein(P170)on surface of K562/A02 cells was tested by immuno-histochemical dyeing method.Apoptosis of K562/A02 cells was measured by DNA gel electrophoresis.Result:① Cytotoxic effect of CB-CIK cells on K562/A02cells was not statistically different from that on K562 cells.Tumor-killing effect of CB-CIK cells on K562/A02 cells was significantly higher than that on CB-LAK cells and CB-CD3AK cells(P0.05).But no significant difference in tumor-killing effect was found between CB-CIK group and PB-CIK group(P0.05).② After treated with CB-CIK cells,expression of P170 on surface of K562/A02 cells reduced obviously.③After 20 hours co-culturing with CB-CIK cells and K562/A02 cells,apoptotic K562/A02 cells displayed clear DNA ladder band on DNA gel electrophoresis.Conclusion:Tumor-killing effect of CB-CIK cells on K562/A02 cells was as efficient as that on K562.The tumor-killing mechanism of CB-CIK cells may be decrease of expression of P170 and induce of apoptosis in leukemia cells.Therefore combination of CB-CIK cells with chemotherapy might be one of new strategy for overcoming MDR in leukemia cells.