Study Of Astragalus Polysaccharides On Maturation Of Dendritic Cell And Promotion Of Specific Anti-tumor Immunity

Objection: The present work comprises two parts. In the first part,theantitumoractivity induced by dendritic cells is studied in vitro to observe the influence ofastragalus polysaccharides on maturation and immunologic function of dendritic cells. Inthe second part, the antitumoractivity induced by dendritic cells is studied in tumor-bearingmice, to investigate the anti-tumor effect of dendritic cells and explore the mechanism.Methods:1. The dendritic cells from human peripheral blood are cultured and induced with IL-4,GM-CSF into immature dendritic cells, which are randomly divided in to3groups. GroupA is treated with astragalus polysaccharides, Group B with TNF-αand Group C withastragalus polysaccharides and TNF-α. The morphotype of dendritic cells is identified byinverted optical microscope and the phenotype of cultured dendritic cells (CD80, CD86) isidentified by flow cytometry.2. Mature dendritic cells loaded with tumor antigens are co-cultured with alloreactiveT cells. MTT is used to detect the effect of astragalus polysaccharides on the function ofdendritic cells in stimulating the proliferation of T cells. ELISA is used to detect the levelof IL-12, IFN-γ in cells culture supernatant.3. Dendritic cells are loaded with tumor antigen and co-cultured with alloreactive Tcells to induce generation of tumor specific cytotoxic T cells(CTL). Then CTL areco-cultured with SGC-7901tumor cells. The killing activity of CTL to SGC-7901cells wastested by LDH release assay.4. Dendritic cells derived from mouse bone marrow are induced maturation andloaded with S180tumor antigen to prepare tumor vaccine. Tumor-bearing mice are divided in to4groups, Group A is injected with NS, Group B with CTX, Group C with dendriticcells induced by astragalus polysaccharides and Group D with dendritic cells induced byTNF-α. The tumor size and survival of the mice are observed.5. ELISA assay is usded to detect the number of IL-12, TNF-α in serum of tumorbearing mice.6. The proliferation of splenocytes is determined by using MTT assay and Th1/Th2was detected by flow cytometry.Results:1. According to the morphology and phenotype, dendritic cells induced by Astragaluspolysaccharides are in accordance with the characteristics of mature dendritic cells.Astragalus polysaccharide can induce dendritic cells maturation.2. CTL activated by dendritic cells can specifically kill tumor cells and the killactivity has no significant difference between the Astragalus polysaccharides group andTNF-α group, suggesting that dendritic cells induced by Astragalus polysaccharides caneffectively activate CTL cells to exert the function of specific anti-tumor.3. Dendritic cells induced by Astragalus polysaccharides can reinforce proliferation ofalloreactive T cells and increase the number of IL-12, IFN-γ in supernatant, suggesting thatDC induced by Astragalus polysaccharides can effectively present antigen to T cell,provide the activation signal, promote the proliferation of T cells and secretion of IFN-γ; atthe same time, dendritic cells are activated to secret IL-12.4. DC vaccine induced by Astragalus polysaccharide can significantly exert antitumoreffect in vivo and prolong the survival time of mice bearing tumor.5. DC vaccine induced by Astragalus polysaccharides can promote the secretion ofTNF-α and IL-12in S180tumor-bearing mice, suggesting that DC vaccine exertsanti-tumor effect through anti-tumor cytokine pathway.6. DC vaccine induced by Astragalus polysaccharide can significantly improve themouse spleen lymphocyte transformation rate, adjust Th1/Th2to drift to Th1, suggestingthat DC vaccine induced by Astragalus polysaccharide can enhance immune function andcell immunity by making the Th1/Th2imbalance transformation to Th1direction.Conclusion: DC vaccine induced by Astragalus polysaccharides can effectivlypresent tumor antigen to T cell, and stimulate T cell to proliferate and activate, increase thesecretion of cytokines, activate CTL to exert specific anti-tumor ability, showing goodantitumor effect in vitro. DC vaccine induced by Astragalus polysaccharides can enhance the antitumor immunity of tumor-bearing mice by promoting T cell proliferation,increasing the secretion of TNF-α, IL-12, inducing Th1/Th2balance to Th1conversion.Finally, DC vaccine can slow down tumor growth speed and prolong the life oftumor-bearing mice.