The Study On Therapeutic Efficacy And Mechanism Of Combination Intratumoral Administration Of Dendritic Cells With Radiotherapy In Mice Bearing Renal Carcinoma

[Objectives] Dendritic cells (DCs), which are currently known to be the most potent professional antigen-presenting cells, have appeared to be central to immune systems because of their abilities to prime naive T cells and initiate a primary immune response. In order to develop methods to enhance loading of DCs with tumor antigens and to examine whether the efficacy of DC-based immunotherapy of cancer could be enhanced by radiotherapy (RT) and to explore its modulatory mechanism, we have established BALB/c murine renal carcinoma models and treated them with different strategies and studied on their mechanisms.[Methods] ① Murine DCs derived from bone marrow progenitors were cultured with rmIL-4 and rmGM-CSF for 6 days, flow cytometry analysis were used to measure cells phenotypes. ②Annexin-V-FITC/PI assay has been used for detection apoptosis rate of Renca cells after radiation. ③ BALB/c mice were inoculated s.c. in the right oxter with 3.52 × 106 Renca tumor cells on day 0, local irradiation was performed on days 14-18. Unpulsed DCs (1 × 106) were administered i.t. on days 13, 18, 21and 24. Mice bearing s.c. Renca tumor cells were treated with intratumoral (i.t.) injections of bone marrow-derived unpulsed DCs in combination with/without local fractionated tumor irradiation. Tumor volumes were measured on days 13,15,17,19,21,23,25,27,29. The curve of tumor growth were described. On day 29 mice were euthanized .Tumor weights were measured . ④Immuno-histochemical staining was used to value expressions of TNF- a and mutant P53 protein. ⑤IL-2, IFN-γ. IL-4, IL-10 which were secreted from isolated splenocytes after treatment were detected by sandwich -ELESA kits.[Results] ①The results of FACS analysis have showed that we haveobtained mature DCs. ?Over a definite dose range, apoptosis rate of Renca cells increased with the elevation of radiation dose.?While RT alone retarded tumor growth to certain extent, DC alone showed little effect on established s.c. Renca tumor growth. However, i.t. DC administration combined with RT inhibited tumor growth in a synergistic manner. ?The results of immuno-histochemical staining showed RT induced significant apoptosis and necrosis in Renca tumor cells. ? DC plus RT therapy was found in this study to significantly enhance the elaboration of both IL-2, IFN- y and IL-4 by splenocytes responding to tumor antigen from treated mice.[Conclusions] ?DC administration combined with RT mediated tumor regression more effectively than DC or RT monotherapy. ?DC administration combined with RT confered systemic antitumor immunity. Cooperative therapy could induce cytokines which can restrain tumors to secrete significiantly. ?RT augmented the antitumor efficacy of DC administration was dependent of tumor apoptosis or necrosis induction. Over a definite dose range, apoptosis rate of Renca cells was related with the elevation of radiation dose. The effect of tumor cells apoptosis induced by RT was related with the expression of P53 and the efficacy of tumor cells necrosis influenced by RT was correlated with the expression of TNF- a.? Direct i.t. injection of DCs was likely to enhance the efficacy of antigen-presenting.