OBJECTIVETo investigate whether the cytokine-induced killer (CIK) cells could acquire multidrug resistance and maintain the original cytotoxic activity after multidrug resistance (mdr1) genes transfection.

METHODSCIK cells were generated from peripheral blood cultured with IFN-gamma, CD(3) monoclonal antibody, IL-2, IL-1 and transfected with a plasmid (pHamdr) containing human mdr1 gene via electroporation. RT-PCR method was used to assay mRNA expression of mdr1 gene in transfected CIK cells, flow cytometry with anti-P-gp monoclonal antibody to detect P-glycoprotein (P-gp) expression on CIK cells membrane, and MTT assay to compare both the multidrug resistance to doxorubicin and colchicines and cytotoxic activity to human mammary cancer cell line MCF7 between transfected and non-transfected CIK cells.

RESULTSmdr1 expression was detected in the transfected CIK cells. There was a strong expression of P-gp on the transfected CIK cells and the percentages of P-gp positive cells were 21% - 37% (average 27%). The IC(50) of transfected CIK cells to doxorubicin was 22.3 - 45.8 times and 6.7 - 11.35 times to colchicines of those of non-transfected CIK cells. The cytotoxic activity to MCF7 remained unchanged (P > 0.05).

CONCLUSIONIt demonstrated that CIK cells transfected with mdr1 gene via electroporation could express multidrug resistance successfully without changes of cytotoxic activity.