Anti-tumor immunity against nasopharyngeal carcinoma by means of LMP2A-specific cytotoxic T lymphocytes induced by dendritic cells

OBJECTIVE: Adoptive immunotherapy with specific cytotoxicity T lymphocytes (CTLs) induced by dendritic cells (DCs) pulsed with tumor antigens plays a crucial role in the immunity against tumor. The purpose of this study was to assess the feasibility and efficacy of latent membrane protein 2A (LMP2A)-specific CTLs immunity against nasopharyngeal carcinoma (NPC) in vitro and in vivo. METHODS: DCs were generated by culturing the monocytes purified from human peripheral blood mononuclear cells (PBMCs) in cytokine cocktail containing granulocyte/macrophage colony-stimulating factor (GM-CSF), interleukin-4 (IL-4), and tumor necrosis factor-alpha (TNF-alpha). The phenotype of mature DCs was analyzed by fluorescence activated cell sorter (FACS). Mature DCs transfected with EBV-LMP2A recombinant adenovirus were co-cultured with autologous PBMCs to induce LMP2A-specific CTLs. The expression of the surface antigens such as CD3, CD4, CD8 and CD56 on CTLs were detected by FACS. The specific cytotoxicity of CTLs on target CNE cells expressing EBV-LMP2A was confirmed using cytotoxicity assay. The anti-tumor effect of LMP2A-specific CTLs in vivo was assessed in the mice tumor models implanted with CNE cells expressing EBV-LMP2A. RESULTS: Mature DCs expressed typically morphologic characteristics and high level of surface markers (CD1a, CD83, CD86, CD80 and HLA-DR). LMP2A-transfected DCs could induce LMP2A-specific CTLs consisting of a majority of CD4+ and CD8+ T cells. Cytotoxicity assay confirmed that the LMP2A-specific CTLs displayed significant cytotoxicity on target CNE cells compared with the controls. The study in vivo demonstrated that the treatment using these specific CTLs retarded the growth of established tumor in the treated mice. CONCLUSION: These findings suggest that DCs transfected with EBV-LMP2A recombinant adenovirus can elicit LMP2A-specific CTLs that have a specific killing effect on NPC in vitro and in vivo. The results provide experimental basis for the further immunotherapy of NPC in clinical trails.