Bioactivity of umbilical cord blood dendritic cells and anti-leukemia effect.

OBJECTIVE: We investigated the effect of umbilical cord blood dendritic cells (DCs) on in vitro proliferation, immunophenotypes and levels of homologous cytokine-induced killer cells (CIK) and the toxicity on leukemia cells. METHOD: Mononuclear cell-induced DC-CIK cells derived from umbilical cord blood were collected and co-cultured in the proportion of 1:5. Cord blood CIK cells or peripheral blood DC-CIK cells were used as control. Phenotypes were analyzed by flow cytometry; vial cell counting was performed using trypan blue, and the killing activity of effector cells against leukemia cells was measured by MTT assay. The levels of interferon-r (IFN-r), tumor necrosis factor-a (TNF-α) and interleukin-12 (IL-12) were determined by ELISA. RESULTS: The proliferative capacity of DC-CIK cells was obviously improved compared with cord blood CIK cells and peripheral blood DC-CIK cells (P<0.05, P<0.05). During the co-culture of cord blood DC-CIK cells, the ratios of CD 3 (+) CD 8 (+) and CD 3 (+) CD 56 (+) cells were obviously higher than that of CIK cells under the same conditions (P<0.05). On day 3 of co-culture, the levels of IL-12, IFN-r and TNF-a in cultured supernatant of cord blood DC-CIK cells were all higher than those secreted by CIK cells cultured alone (P<0.01, P<0.05, P<0.05). When the effector to target ratio was 2.5-20:1, the killing effect of cord blood DC-CIK cells against each subtype of acute leukemia cells was obviously higher than that of CIK cells (P<0.05). No significant differences in killing effect were observed for different subtypes. This finding was consistent with the killing effect of peripheral blood DC-CIK cells against leukemia cells. CONCLUSION: Cord blood DCs can enhance the proliferative capacity of homologous CIK cells and its anti-leukemia effect. Though cord blood DC-CIK cells showed a higher proliferative capacity than peripheral blood DC-CIK cells, the two types of DC-CIK cells did not differ significantly in terms of cytoxicity. With a high availability and the low probability of graft rejection reaction, cord blood DC-CIK cells have a brighter prospect for application in immunotherapy.

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

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.

Biological activity of DC-CIK cells and its effect against leukemia cells in vitro.

This study was aimed to investigate the effect of dendritic cells (DC) on the proliferation capability, immunophenotype changes, level of secreted cytokines and activity against leukemia of cytokine-induced killer (CIK) cells in vitro. DCs and CIK cells were induced from peripheral blood mononuclear cells of healthy volunteers. They were co-cultured meanwhile CIK cells were cultured alone as controls. Increased number of cells were counted by trypan-blue staining; the killing activity was detected by MTT assay; immunophenotype changes were analyzed by flow cytometry; the IL-12 and INF-gamma levels of the cultured supernatants were detected by ELISA kits. The results showed that the proliferation capability of DC-CIK cells was significantly higher than that of CIK cells (p < 0.05). Under the same condition, the ratio of double positive cells such as CD3(+) CD8(+), CD3(+) CD56(+) in CIK cells was significantly enhanced by co-cultured with DC cells (p < 0.05). The levels of IL-12 and INF-gamma in cultured supernatants of DC-CIK cells increased noticeably on day 3 as compared with CIK cells cultured alone (p < 0.01, p < 0.05). Within the effector-target ratio range between 5:1 to 40:1, the activity of DC-CIK cells against leukemia cells were much higher than that of CIK cells (p < 0.05), and this effect showed a positive correlation with the effector-target ratio. It is concluded that the proliferation capability of DC-CIK cells, the level of their secreted cytokines and their activity against leukemia cells are significantly higher than those of CIK cells. This research may suggest an approach for clinical immunotherapy against leukemia with DC-CIK cells.