An important reason for the immune escape of tumors is that tumor cells under-express or do not express MHC-like molecules and co-stimulatory molecules, so that antigens cannot be effectively presented to T cells to produce specific anti-tumor effects, causing tumor cells to evade the body’s immune surveillance and leading to tumor formation and development [4]. As the initiator and regulator of the immune response in the body, DCs are extremely important in the body’s anti-tumor immune response. The preparation of efficient DC vaccines using mature DCs loaded with tumor antigens is a hot topic of research and is crucial to induce the production of tumor-specific CTLs [5]. Therefore, stimulating effective T cell-mediated antitumor immune responses is the key to improve the effectiveness of tumor immunotherapy. According to the dual-signal theory of T-lymphocyte activation, antigen alone cannot activate T-lymphocytes, and antigen must be presented by APCs that can provide auxiliary signals to effectively induce the formation of CTLs and exert anti-tumor effects [6]. In contrast, DCs are the most powerful APCs in vivo, activating T lymphocytes in vivo and stimulating the body’s initial immune response [7]; promoting the generation of Th and CTLs. It was found that tumor antigens cannot effectively induce antitumor immunity without being presented by DCs [8]. Therefore, expanding DCs in vitro and loading them with the corresponding tumor antigens, inducing maturation, and then returning them to the body can resist the aforementioned inhibitory effects and appear to be important for tumor peri-immunotherapy. In this experiment, DCs were induced in vitro from healthy adult PBMC with the combination of GM-CSF, IL-4 and TNF-α. The killing rate of DCs against the same type of gastric cancer cell lines with different degrees of differentiation could be as high as 70.45%, suggesting that DCs effectively captured and presented gastric cancer antigens and induced gastric cancer antigen-specific CTLs, producing an efficient anti-gastric cancer effect, indicating that although they are the same human gastric cancer This indicates that although they are both human gastric cancer cell lines, their differentiation degree is different and their antigens are different. However, on the other hand, it suggests that they are the same gastric cancer cell line with similar antigens, thus exhibiting a high killing effect, which provides a basis for the application of a shared vaccine for clinical gastric cancer. The experiment also showed that the specific CTLs had no significant killing effect on other types of lung cancer cell line A549, suggesting that gastric cancer antigen-sensitized DC-induced CTLs are highly specific for gastric cancer, and this good specific killing activity indicates that immunotherapy with CTLs stimulated by gastric cancer antigen-sensitized DC vaccine can be used as a new treatment for gastric cancer patients, fully showing the antigen-presenting role of DC in The important role of DC antigen presentation in the antitumor immune response was well demonstrated. The possible mechanisms are: DCs have a large number of dendritic protrusions on the surface, which make them favorable for large exposure to antigen and presentation to gastric cancer cells; DCs highly express MHCI, class II molecules and co-stimulatory molecules such as CD80/CD86, which provide signal stimulation for adequate activation of gastric cancer cells; DCs secrete a variety of cytokines such as IL-12, which can maintain and enhance the activity of gastric cancer cells. Meanwhile, IL-12 can influence the polarization direction of T cells, up-regulate IFN-γ expression, and enhance the killing activity by secreting IFN-γ and so on. After applying gastric cancer antigen-sensitized DCs to activate effector T cells, the analysis of tumor cells in different phases of cytokinesis and proliferation can understand the extent to which gastric cancer target cell division and proliferation are affected by DC effector cells. In this experiment, we interfered with the division and proliferation of tumor cells in resting culture by applying gastric cancer antigen-sensitized DC-activated T cells. The results showed that the effector T cells activated by gastric cancer antigen-sensitized DC produced a significant inhibitory effect on the proliferation of the three gastric cancer cells, while the inhibitory effect on A549 was weaker (P<0.01), reflecting the effective control effect of gastric cancer antigen-sensitized DC on the proliferation of gastric cancer cells in vitro. Meanwhile, the experimental results also showed that the apoptosis rate of the three gastric cancer cell strains showed an increasing trend, while the apoptosis rate of A549 did not show any significant down-regulation (P<0.01). CTL induced apoptosis in gastric cancer cells, which may be one of the mechanisms of DC tumor vaccine against gastric cancer. This result will provide theoretical and experimental basis for the application of DC in gastric cancer immunotherapy.