Apoptotic-tumor-cell-loaded Dendritic Cells Can Induce Cytotoxic T Lymphocytes And Elicit The Specific Tumor Immunity

Dendritic cells (DC), the initiator and modulator of immune response , are the most powerful professional antigen-presenting cells (APC). Recent studies indicated that DC have the most power to activate tumor specific CTL, therefore, DC are applied in the therapy of tumors, e. g: B cell lymphoma, prostate cancer, multiple myeloma, breast cancer. But the optimal method for induction of tumor specific CTL hasn't been determined.Our studies focused on the role and mechanism of DC in the activation and proliferation of tumor antigen specific CTL and establishing an optimal method for producing tumor antigen specific CTL in vitro. We used PBMC-derived DC loaded with apoptotic Daudi cells, which were irradiated by 60Co Y after incubation with agonist CD40mAb ( 5cl 1, 5 ? g/ml) for 24h. Tumor specific CTL were activated by the mature apoptotic-tumor-cell-loaded DC in the presence of IL-2 and CD28mAb, IL-15, IL-7. The expression of membrane molecules on DC and CTL were analyzed by FCM; IL-12, IL-10, IFN- Y concentrations of T cell culture supernatants were measured by ELISA; Proliferation andcytotoxicity of CTL were analyzed by 3H-thymidine incorporation and a 4-h 51Cr release assay respectively. Our results showed that (1) following incubation with agonist CD40mAb (5 ?g/ml) ,then irradiated by 60Co ? , the apoptotic rate of Daudi cells was significantly increased; (2) After treatment of CD40mAb (5 ?g/ml), the expressions of CD la, CD80, CD83, CD86 , HLA-DR on tumor-loaded DC were upregulated and concentration of IL-12 in the supernatant were increased. (3) Apoptotic-tumor-cell-loaded DC, in addition with agonist CD28mAb, IL-2, IL-15 could induce efficient quality and large quantity of tumor specific cytotoxic T lymphocytes, it also could downregulate the expression of Fas on CTL. Conclusion: Apoptotic-tumor-cell-loaded DC induced maturation by CD40mAb could efficiently induce the activation and proliferation of tumor specific CTL, and the combination of IL-2, IL-15, CD28mAb was a very powerful method to expand antigen specific CTL in vitro.