Influence of dendritic cells on biological activity of the homologous CIK cells and its anti-leukemia effect in vitro

Abstract

This study was aimed to investigate the effect of cord blood dendritic cells (DCs) on the in vitro proliferation capability, immunophenotype changes, level of secreted cytokines and activity against leukemia cells of the homologous cytokine-induced killer (CIK) cells. DCs and CIK cells were induced from cord blood mononuclear cells. They were co-cultured at the ratio of 1:5, and CIK cells from cord blood or DC-CIK cells from peripheral blood were cultured as controls. Immunophenotypic changes were analyzed by flow cytometry, increased number of cells were counted by trypan-blue staining, the killing activity to leukemia cells was assayed by MTT, the levels of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α) and interleukin-12 (IL-12) in the cultured supernatant were detected by ELISA. The results showed that the proliferation capability of cord blood DC-CIK cells was significantly higher than that of cord blood CIK cells and peripheral blood DC-CIK cells (p < 0.05 and p < 0.05). Under the same condition, the rate of double positive cells with CD3(+)CD8(+) and CD3(+)CD56(+) in CIK cells was significantly enhanced by co-culture with cord blood DCs (p < 0.05). The level of IL-12, IFN-γ, and TNF-α in cultured supernatants of cord blood DC-CIK cells increased noticeably on day 3 as compared with CIK cells cultured alone (p < 0.01, p < 0.05, p < 0.05). Within the effector-target ratio range between 2.5:1 to 20:1, the activity of cord blood DC-CIK cells against all subtypes of acute leukemia cells was much higher than that of CIK cells (p < 0.05), and there was no significant difference among all subtypes of acute leukemia cells, which was the same with the killing effect of peripheral blood DC-CIK cells against leukemia cells. It is concluded that the proliferation capability and anti-leukemia effect of the homologous CIK cells can be enhanced by cord blood DCs. The proliferation capability of cord blood DC-CIK cells is stronger than that of peripheral blood DC-CIK cells, but there is no significant differences of cytotoxicity between DCs and CIK cells. As the cord blood is easily gained and does not easily cause a serious graft rejection, the DC-CIK cells should be clinically applied more extensively as novel immune therapy.