Abstract

Despite the large number of potentially cytotoxic tumor-infiltrating (TIL) and tumor-associated (TAL) lymphocytes accumulated in the peritoneal cavity ascitic fluid and tumor tissue, advanced ovarian cancer is a progressive disease, suggesting that TIL and TAL populations eventually become functionally suppressed in vivo. Dendritic cells (DC) are the most powerful professional antigen presenting cells known in humans and recently, ovarian tumor antigen pulsed DC have been shown to elicit tumor specific human leukocyte antigens (HLA)-class I-restricted cytotoxicity from the peripheral blood of advanced ovarian cancer patients. In this study, we have evaluated the potential of tumor antigen-pulsed fully mature DC stimulation in restoring tumor-specific cytotoxicity in anergic TIL populations from advanced ovarian cancer patients. In addition, we have compared tumor-specific T-cell responses induced by tumor antigen-loaded DC in TIL to those induced in TAL and peripheral blood lymphocytes (PBL). DC stimulation induced powerful cytotoxicity against autologous tumor target cells in TIL-derived CD8+ T-cells from all patients tested, while autologous Epstein–Barr virus (EBV)-transformed lymphoblastoid cell lines (LCL) were not lysed. Killing of autologous tumor cells was higher by CD8+ T-cells from TIL compared to PBL and TAL (P < 0.01) and was more strongly inhibited by anti-HLA class I MAb (P < 0.05 compared to PBL and TAL). Phenotypically, all cytotoxic T lymphocyte (CTL) populations were CD3+/CD8+, with variable levels of CD56 expression. Finally, although a marked Type 1 cytokine bias [ie, interferon-gamma/interleukin-4 (IFN-γ^high/IL-4^low)] was observable in all DC-stimulated CD8+ T-cell populations, TIL derived CD8+ T-cells showed a higher percentage of IFN-γ positive cells compared to TAL and PBL. Taken together, these data show that tumor lysate-pulsed DC can consistently restore strong CD8+ CTL responses from TIL against autologous ovarian cancer cells. DC-stimulated TIL may represent a superior source of tumor-specific CTL for adoptive T-cell immunotherapy for advanced ovarian cancer.