Study On Specific Anti-tumor Immunity Mediated By Dendritic Cells Pulsed With Breast Cancer Lysates From Multi-drug Resistant Cells And Sensitive Cells

Objective Dendritic cells (DCs) are the most potent professional antigen-presenting cells in vivo as yet, are capable of generating tumor-specific immunity and can be used important vectors in anti-tumor immunity. Malignant tumor is sensitive to chemotherapy, but multi-drug resistance (MDR) developed by tumor cells often induces failure of chemotherapy. DC-based tumor vaccines have shown efficacy in anti-tumor immunity responses in vitro and in vivo. However, can P-gp be used as a target-antigen for the immunotherapy of cancer? Can DCs pulsed with lysates from multi-drug resistant (MDR) tumor cells expressed high P-glycoprotein induce T cell into specific cytotoxicity T lymphocyte (CTL)? Can a specific cytotoxicity be mediated by these DCs? What's the difference between MCF-7/ADR-DC and MCF-7-DC? In order to explore these questions the experiments were carried out.Methods Bone marrow mononuclear cells (BMMNCs) were isolated fromhealthy donors by Ficoll density gradient centrifugation and were induced to obtain DCs in complete RPMI-1640 culture medium supplemented with GM-CSF (1000U/ml), IL-4 (500U/ml) and TNF-a (100ng/ml). Then immature DCs (imDCs) were pulsed with breast cancer lysates from multi-drug resistant MCF-7/ADR cells and MCF-7 cells respectively. The morphologic features were observed with optical microscopy and the phenotypes of DCs were analyzed by flow cytometry (FACS). The proliferative activity and cytotoxicity of CTL were measured with MTT assay.Results It was demonstrated that DCs derived from BMMNCs showed the typical morphology of dendritic cells. The levels of CDla, CD83, HLA-DRexpression on DCs were obviously higher than those before culture (P<0.01). The induced cells could prime CD8+T lymphocytes of normal peripheral blood mononuclear cells (PBMNCs). DCs pulsed with lysates from MCF-7/ADR and MCF-7 cells displayed significantly specific cytotoxic activity against MCF-7/ADR or MCF-7 cells respectively. The cytotoxic activities were higher than simple DC group and T cell group (P<0.01). More importantly, cytotoxicity mediated by MCF-7/ADR-DC was stronger than that by MCF-7-DC against MCF-7/ADR cells(53.67+2.10% versus 41.83 + 1.63% at effectors: targets of 20:l,p<0.01).Conclusions This study indicates that functional DCs with enhancedantigen-presenting ability could be differentiated from BMMNCs pulsed with lysates of multi-drug resistant MCF-7/ADR cells expressed high p-glycoprotein and sensitive MCF-7 cells in the presence of GM-CSF, IL-4 and TNF-a, that these cells could mediate effectively specific CTL immune response. Especially, the CTL induced by MCF-7/ADR-DC could strongly mediate cytotoxicity against multi-drug resistant MCF-7/ADR cells than those induced by MCF-7-DC. This maybe provides an experimental basis for immunotherapy to overcome multi-drug resistance tumors.