Mature CD83+ dendritic cells infected with recombinant gp100 vaccinia virus stimulate potent antimelanoma T cells

Background: Mature dendritic cells (DCs) are potent antigen-presenting cells that activate naive T lymphocytes and initiate cellular immune responses. The ability of CD83(+) mature DCS infected with vaccinia virus encoding the gp100 melanoma transgene (rV-gp100) to stimulate an antimelanoma CD8(+) T-cell response was investigated. Methods: Monocyte-derived immature or CD83(+) mature DCs were infected with rV-gp100. The activation state of the DCs and the expression of gp100 protein were evaluated by flow cytometry. The reactivity of antimelanoma CD8(+) T cells was confirmed by measuring specific interferon gamma secretion by using enzyme-linked immunosorbent assay in a mixed-tumor lymphocyte culture. Results: Both immature and CD83(+) mature DCs expressed gp100 protein when the DCs were infected with rV-gp100. Calcium-signaling agents were required to induce maturation of both infected and noninfected immature DCs. Only rV-gp100-infected CD83(+) DCs induced CD8(+) T cells, after a single stimulation that recognized both peptide-pulsed target cells to multiple gp100 epitopes and a melanoma cell line that endogenously expressed gp100 antigen. Conclusions: CD83(+) DCs transduced with rV-gp100 are capable of generating a strong CD8(+) T-cell response against melanoma tumor cells. Expression of melanoma antigens by mature DCs offers the potential advantage of presenting multiple endogenously processed T-cell epitopes and using multiple HLA restriction elements for antimelanoma vaccine therapy.