Generation of peptide-specific cytotoxic T lymphocytes using allogeneic dendritic cells capable of lysing human pancreatic cancer cells

Background. Dendritic cells (DCs) are potent antigen presenting cells (APCs), able to efficiently induce primary T cell-mediated responses to foreign antigens. In earlier studies we were able to identify a histocompatibility antigen (HLA)-A2-restricted nine amino acid peptide (GP2, peptide 654-662) from the transmembrane portion of the protooncogene HER2/neu as a tumor-associated antigen (TAA) in human pancreatic cancer. Methods. Peripheral blood mononuclear cells [PBMCs] of HLA-A2⁺ and HLA-A2- healthy volunteers were isolated. PBMCs were grown with initial anti-CD3, low-dose interleukin-2 (IL-2), and peptide-pulsed DC stimulation. T-cell lines were analyzed in functional studies. Results. After 4 weeks, T-cell cultures were more than 50% CD8⁺. All peptide-pulsed T cells significantly lysed APC pulsed with the immunizing antigen in an HLA-A2 restricted fashion. Furthermore, HLA-A2⁺, HER2/neu⁺ human pancreatic cancer cells were lysed significantly higher than HLA-A2-HER2/neu⁺ pancreatic cancer cells. Transfection of an HLA-A2- pancreatic cancer cell line with the HLA-A2 gene resulted in a significantly higher lysis of the transfected cell line compared to the wild type. In HLA-A2⁺ pancreatic cancer targets, specific lysis was HLA-A2 restricted. Conclusion. The ability to use DCs for presentation of either tumor or peptide antigen in an HLA-restricted fashion to stimulate T-cell proliferation, as well as cytotoxicity, demonstrates the potential of this technology for future development of a pancreatic cancer vaccine.