RESUMO
Dendritic cells (DCs) derived from bone marrow cells are specialized cells for the uptake, processing, and presentation of foreign and self-antigens. The study indicated that re-transfusion of DCs pulsed with tumor-associated antigen can induce an vigorous specific anti-tumor response in clinic. The present study was aimed to investigate the enhancing effect of DCs derived from human cord blood on T cells in killing tumor cells. Human cord blood mononuclear cells were isolated from human cord blood by density gradient centrifugation using lymphocyte separating medium, and cord blood mononuclear cells were obtained by adherence and cultured in a liquid culture system with GM-CSF and IL-4 for 15 days. Then the cells were analyzed for phenotypes of CD1a by indirect immunofluorescence. The capacity of DCs to initiate T cell-dependent anti-tumor immune responses was assayed by MTT kit. The ratios of DCs to tumor cells in experimental groups were 20:1, 50:1 and 100:1 respectively. The DCs were not added in control group. The results indicated that in the presence of GM-CSF and IL-4, the DCs with typical morphological features at days 15 were observed. At that time, (43.12 +/- 5.83)% CD1a(+) cells were obtained. In addition to these phenotypic properties, the DC of experimental groups could remarkably initiate T cell-dependent anti-tumor immune responses with different ratios compared with control group (P < 0.01), there were no significant difference of killing effects between 100:1 and 50:1 groups (P > 0.05), and killing effect of DC in 20:1 group was higher than that in 100:1 or 50:1 groups (P < 0.05). It is concluded that human cord blood mononuclear cells can serve as a better source of DC, which can promote the capacity to initiate T cell-dependent anti-tumor immune responses.
