[Assessment of lymphocytic function in vitro stimulated by specific tumor polypeptide combined with dendritic cells].

OBJECTIVE: To assess the activation function of specific tumor polypeptide for dendritic cell vaccine on lymphocytes proliferation, production of cytokines and killing activity in vitro by using dendritic cells as antigen presenting vector. METHODS: Peripheral blood dendritic cells (DC) and cytokine-induced killer (CIK) were isolated and cultured by adherent culture method; CCK-8 method was used to assess the proliferation function of lymphocytes and the killing function of lymphocytes to tumor cells; enzyme-linked immunospot assay method was used to evaluate the secretion function of cytokines. The experiment was divided into tumor polypeptide group (peptide with DC-CIK), DC-CIK group and CIK group. RESULTS: With presence of interleukin-2 (IL-2) in the culture system, the lymphocyte proliferation of the three groups was obvious. The absorbance at 450 nm of tumor polypeptide group was significantly higher than that of CIK group at the time points day 4 and day 6 (day 4: Z=-3.79, P < 0.001; day 6: Z =-2.95, P < 0.01). The absorbance at 450 nm of group tumor polypeptide was significantly higher than that of DC-CIK group on day 4 (Z=-2.02, P < 0.05). Without IL-2 in the culture system, lymphocytes proliferated slowly in all the three groups, and there was no significant difference in 450 nm absorbance at each time point. The levels of IL-4 (Z=-2.61, P < 0.01), granulocyte-macrophage colony-stimulation factor (GM-CSF, Z=-3.85, P < 0.001), interferon- γ (IFN- γ, Z=-3.56, P < 0.001) and tumor necrosis factor-α (TNF-ɑ, Z=-3.40, P < 0.001) of tumor polypeptide group were higher than those of CIK group. There was no significant difference in the production of cytokines except IL-4 (Z=-2.15, P < 0.05) when tumor polypeptide group was compared with DC-CIK group. The production of IFN-γ (Z=-2.44, P < 0.05), TNF-ɑ (Z=-2.26, P < 0.05) and GM-CSF (Z=-3.73, P < 0.001) in DC-CIK group were higher than those of CIK group. Although there was no significant difference in killing activity between tumor polypeptide group, DC-CIK group and CIK group at hour 18 and hour 24, and the killing activity of tumor polypeptide group was higher than that of the other two groups. CONCLUSION: Tumor peptide combined with dendritic cells can improve the proliferation activity of CIK cells in vitro, and increase the secretion of several cytokines.