Objective: The purpose of this study was to evaluate the potential of dendritic cells pulsed with whole-tumor extracts derived from autologous ovarian cancer cells in eliciting a tumor-specific cytotoxic T-cell response in vitro from patients with advanced ovarian cancer.
Study design: CD8(+) T lymphocytes stimulated in vitro with autologous ovarian tumor lysate-pulsed dendritic cells were tested for their ability to induce a human leukocyte antigen class I-restricted cytotoxic T-lymphocyte response able to specifically kill autologous tumor cells in standard 6-hour chromium 51 cytotoxicity assays. In addition, to correlate cytotoxic activity by cytotoxic T-lymphocytes with a particular lymphoid subset, 2-color flow cytometric analysis of intracellular cytokine expression (interferon gamma and interleukin 4) at the single-cell level was performed.
Results: Cytotoxic T lymphocytes specific for autologous ovarian tumor cells were elicited from 3 patients with advanced ovarian cancer. Although cytotoxic T-lymphocyte populations expressed strong cytolytic activity against autologous tumor cells, they did not lyse concanavalin A-stimulated autologous lymphocytes or autologous Epstein-Barr virus-transformed lymphoblastoid cell lines and showed negligible cytotoxicity against the natural killer cell-sensitive cell line K-562. Cytotoxic effect against the autologous tumor cells was inhibited by an anti-human leukocyte antigen class I monoclonal antibody (W6/32). It is interesting that CD8(+) cytotoxic T lymphocytes expressed variable levels of CD56, a marker that may be associated with high cytotoxic activity. Finally, most of the tumor-specific CD8(+) T cells exhibited a T(H)1 cytokine bias, and a high percentage of interferon gamma expressors among cytotoxic T lymphocytes was correlated with higher cytotoxic activity.
Conclusion: These data show that tumor lysate-pulsed dendritic cells can consistently induce in vitro specific CD8(+) cytotoxic T lymphocytes able to kill autologous tumor cells from patients with advanced stage ovarian cancer. This novel approach may have important implications for the treatment of residual or resistant disease with active or adoptive immunotherapy after standard surgical and cytotoxic treatment.