Tumor antigen pulsed dendritic cells enhance the cytolytic activity of tumor infiltrating lymphocytes in human hepatocellular cancer

Objective: Tumor infiltrating lymphocytes (TILs) stimulated with interleukin -2 (IL-2) ex vivo have been successfully used therapeutically in some cancer patients, but their potency in eliciting an effective anti-tumor response is variable. We have tried to augment killing activity of tumor infiltrating lymphocytes derived from hepato- cellular carcinoma (HCC) using autologous monocytes derived dendritic cells. Methods: Tumor infiltrating lymphocytes (TILs) from 6 patient with hepatocellular carcinoma were isolated and the phenotype were further characterized. From the same patients, autologous dendritic cells were generated from CD14(+) monocytes that were cultured for days in the presence of granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin 4 (IL-4). Those professional antigen presenting cells were pulsed with whole autologous hepatoma tumor lysates (pDC). TILs were cocultured with pDC or unpulsed DC. To assess the cytotoxic potency of TILs, the ability to lyse the tumor cell targets K652, Daudi and an allogeneic HCC celline was determined in a standard cytotoxic assay. Results: Tumor cells targets in vitro are poorly lysed by tumor infiltrating lymphocytes indicating T-cellhyporesponsiveness. In contrast, the killing activity of HCC derived TILs against Daudi (9, 15% +/- 7,5) and allogeneic HCC tumor target (18,2% +/- 9,2) could be significantly augmented when stimulated with pDC (Daudi: 38% +/- 6,8 and allogeneic HCC: 55% +/- 10). The killing activity of TILs against K562 was unaffected by pDC. Conclusion: The low cytotoxic activity profile of HCC derived TILs in vitro can be increased by tumor lysate pulsed dendritic cells and may therefore be more effective in vivo when used for adoptive immunotherapy.