Whole-tumor-antigen-pulsed dendritic cells elicit cytotoxic T-cell response against pediatric nasopharyngeal carcinoma in vitro

Nasopharyngeal carcinoma (NPC) is endemic in Southeast Asia. Although dendritic cell (DC)-based vaccine has emerged as a promising immunotherapy for various malignancies, its use in pediatric nasopharyngeal carcinoma (PNPC) has not been addressed. In this study, DCs isolated from peripheral blood monocytes of three pediatric patients with advanced (stage IV) NPC were incubated with whole-tumor-antigen preparations and differentiated into immature DCs in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4, and then underwent maturation when exposed to tumor necrosis factor-α. Upon maturation, DCs acquired the ability to stimulate T-cell proliferation as examined by [³H]-thymidine incorporation and the ability of these T-cells to secrete interferon-γ as determined by enzyme-linked immunosorbent spot assay. Cytotoxic assay revealed that mature tumor-antigen-pulsed DCs induced cytotoxic activity of the T-cells against both autologous and allogeneic NPC tumor cells (including NPC tumor cells from a different individual or from CNE-2Z, a poorly differentiated human NPC cell line). Blocking HLA class I molecules by W6/32 inhibited T-cell-mediated cytotoxic activity in both autologous and allogeneic settings. Our results indicate that DCs pulsed with whole-tumor-antigen can effectively activate HLA class I-restricted cytotoxic T-cells in vitro, and thus provide experimental basis for their future clinical use in PNPC.