Dendritic cells infected with a vaccinia vector carrying the human gp100 gene simultaneously present multiple specificities and elicit high-affinity T cells reactive to multiple epitopes and restricted by HLA-A2 and-A3

To investigate the ability of human dendritic cells (DC) to process and pre sent multiple epitopes from the gp100 melanoma tumor-associated Ags (TAA), DC from melanoma patients expressing HLA-A2 and HLA-A3 were pulsed with gp1 00-derived peptides G(9)154, G(9)209, or G(9)280 or were infected with a va ccinia vector (Vac-Pmel/gp100) containing the gene for gp100 and used to el icit CTL from autologous PBL, CTL were also generated after stimulation of PBL with autologous tumor. CTL induced with autologous tumor stimulation de monstrated HLA-AZ-restricted, gp100-specific lysis of autologous and alloge neic turners and no lysis of HLA-A3-expressing, gp100(+) target cells. CTL generated by G(9)154, G(9)209, or G(9)280 peptide-pulsed, DC-lysed, HLA-A2- matched EBV transformed B cells pulsed with the corresponding peptide. CTL generated by Vac-Pmel/gp100-infected DC (DC/Pmel) lysed HLA-A2- or HLA-AS-m atched B cell lines pulsed with the HLA-A2-restricted G(9)154, G(9)209, or G(9)280 or with the HLA-A3-restricted G(9)17 peptide derived from gp100, Fu rthermore, these DC/Pmel-induced CTL demonstrated potent cytotoxicity again st allogeneic HLA-A2- or HLA-A3-matched gp100(+) melanoma cells and autolog ous tumor. We conclude that DC-expressing TAA present multiple gp100 epitop es in the context of multiple HLA class I-restricting alleles and elicit CT L that recognize multiple gp100 derived peptides in the context of multiple KLA class I alleles, The data suggest that for tumor immunotherapy, geneti cally modified DC that express an entire TAA may present the full array of possible CTL epitopes in the context of all possible HLA alleles and may be superior to DC pulsed with limited numbers of defined peptides.