Induction of anti-leukemic immunity of dendritic cells derived from multidrug resistant leukemia K562/A02 cells with high expression of P-glycoprotein and sensitive K562 cells

This study was aimed to investigate and compare the anti-leukemic effect mediated by dendritic cells (DC) derived from multidrug resistant (MDR) leukemia K562/A02 cells with high expression of p-glycoprotein (P-gp) and sensitive K562 cells. Multidrug resistant K562/A02 cell line and sensitive K562 cell line from chronic myeloid leukemia (CML) were induced for differentiating to DC in complete RPMI 1640 culture medium supplemented with GM-CSF (1 000 U/ml), IL-4 (500 U/ml) and TNF-alpha (100 ng/ml) for 14 days. The morphologic features of DC were observed by means of optical microscopy and the phenotype of DC was detected by flow cytometry. T-cell stimulating activity was determined by allogeneic lymphocyte reaction (allo-MLR). Cytotoxic activity was measured by MTT assay. The results indicated that DC derived from K562/A02 cells and K562 cells similarly showed the typical morphology of dendritic cell and expressed the surface differentiation antigens and costimulatory molecules CD1a, CD83, HLA-DR, CD80 and CD86 of DC. In allo-MLR, K562/A02-DC had a higher capacity to induce lymphocyte proliferation, compared with K562-DC (P < 0.05). K562/A02-DC and K562-DC could similarly generate specific cytotoxic activity against K562/A02 cells or K562 cells respectively, but low reactivity against HL-60 cells. More importantly, the cytotoxic activity mediated by K562/A02-DC was stronger than that by K562-DC against K562/A02 cells or HL-60/VCR cells (P < 0.01, respectively). It is concluded that functional DC can be differentiated from multidrug resistant leukemia K562/A02 cells as well as sensitive K562 cells in the presence of GM-CSF, IL-4 and TNF-alpha. Especially, DC derived from K562/A02 cells can induced a p-glycoprotein specific anti-leukemic immunity.