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An experimental study on DC-CIK cells' immuno effects on killing gastric cancer cells in vitro

Hou-Jun Cao, Ti-Ye Sun, Wei Yan, Chun-Min Yang, Long-Fang Zhang, Ying Jin, Jie Qiu, Hai-Xiang Hu, Xuan Wei

Objective: To investigate the anti-gastric cancer immuno effects of DC-CIKs against gastric cancer cells by co-culturing Dendritic Cells (DCs) with Cytokine-Induced Killer cells (CIKs) derived from peripheral blood mononuclear cells of patients with gastric carcinoma.

Methods: Collecting 30 ml peripheral blood of patient of gastric cancer, we separate peripheral blood with lymphocyte separation liquid to obtain mononuclear cells respectively, and used for generating DC with the treatment of recombinant human Granulocyte Macrophage Coliny Stimulating Factor (rhGMCSF) and recombinant human Interleukin-4 (rhIL-4) as well producing CIK with interferon-γ (IFN-γ), CD3 and rhIL-2 in vitro, mixing SGC-7901 cells of DC and CIK cells and then DC and CIK were cocultured according to the ratio of 1:10 to produce DC-CIK. The experiment was performed with three groups composed of DC-CIK group, DC group and CIK group. After 14 d of co-culture, increased number of cells were counted by trypan blue staining, cytotoxic activity against SGC-7901 cells in three groups were detected by MTT assay. The Flow Cytometry (FCM) was used to measure the antigen expression of the CD_1a, CD₈₃, CD₈₆, CD₈₀, CD₄₀, HLA-DR and the lymphocyte subsets of CD3+, CD3+CD8+ and CD3+CD56+ of the three groups cells. Levels of Interleukin-12 (IL-12), Interleukin-4 (IL-4), the Interferon-γ (IFN-γ) and Tumor Necrosis Factor-α (TNF-α) in the supernatants of DC-CIK, DC and CIK cells culture were detected by Enzyme-Linked Immunosorbent Assay (ELISA).

Results: After culturing for 14 d in vitro, the proliferation capability and the cells percentage of antigen expression of peripheral blood DC-CIK cells was significantly higher than that of DC and CIK cells (p<0.01). The killing activity of DC-CIK cells was significantly higher than that of DC and CIK cells, with effect-target ratio increasing, the killing activity increased gradually (p=0.000). CD3+CD8+, CD3+CD56+ double positive cells in DC-CIK co-culture were significantly increased than that DC and CIK groups under the same conditions (p<0.01). The concentrations of IL-12, IL-4, IFN-γ and TNF-αin the cultural super mutant in the DC-CIK group were significantly higher than DC and CIK groups (p=0.000). However, there is no statistics difference among the DC and CIK groups (p>0.05).

Conclusion: DC-CIK can induce potent immunological effect against gastric cancer cells. Immuno efficacy of DC-CIK against gastric cancer is relevant to cytokine and cytotoxicity, which provides theoretical and experimental basis for the clinical immunotherapy of gastric cancer.