Cervical cancer is the second most common gynecological cancer amongst women worldwide. Despite optimized protocols, standard treatments still face several disadvantages. Therefore, novel research aims to develop immune-based therapies such as the loading of dendritic cells (DC) with tumor antigens for the induction of cellular anti-tumor immunity. For this purpose, we –initially - used an HLA-A2-restricted HPV-16 E711-20 peptide for the loading of DC in order to induce an in vitro T cell response . Peptide-pulsed DC were brought into coculture with autologous CD8+ T cells. After 4 weekly restimulations with peptide-pulsed DC, cultured T cells were subsequently analyzed for antigen specificity by IFN-gamma ELISPOT after restimulation with target cells or control cells. With this ELISPOT assay, we detected E7-specific IFN-gamma secretion by CD8+ T cells in 5/5 healthy donors. There are however some limitations linked to the use of peptides. Peptide-pulsed dendritic cells express only one tumor-associated epitope and this in an HLA-restricted manner. To overcome these limitations, we are exploring HPV type 16 E7 mRNA-electroporation in dendritic cells in an immune activating setting. We already proved that electroporated mRNA still can be detected by means of RT-PCR several days after electroporation. In conclusion, we show that peptide-pulsed dendritic cells are able to stimulate a primary HPV type 16 specific immune response. These experiments concern the development of cytotoxic T cell cultivation protocols in preclinical vaccination strategies. In future studies, we will investigate whether mRNA-electroporation contributes to the generation of a more efficient immune response in vitro.
[Proc Amer Assoc Cancer Res, Volume 45, 2004]