Eliciting cytotoxic T lymphocytes against human laryngeal cancer-derived antigens: evaluation of dendritic cells pulsed with a heat-treated tumor lysate and other antigen-loading strategies for dendritic-cell-based vaccination

Background: Dendritic cells (DCs) have been used successfully in clinical pilot studies. However, tumor-specific immunity and clinical responses were only induced in certain cancer patients. It has been well documented that immunotherapy efficacy can be optimized for responses using antigen pulsing. Methods: The human laryngeal squamous cell cancer (LSCC) cell line SNU899 was used to evaluate the in vitro anti-tumor efficacy of three different preparations of dendritic cell (DC) vaccines consisting of either whole tumor cells or their derivatives including: i) DCs pulsed with a tumor cell supernatant (DC-TCS), ii) DCs pulsed with whole-cell tumor stressed lysate (DC-TSL), and iii) DCs pulsed with irradiated tumor cells (DC-ITC). Results: Our results showed that DC-TSL is an effective source of tumor-associated antigens (TAAs) for pulsing DCs. DC-TSL induced the highest expansion of TAA-specific T cells, the strongest Th1 cytokine response, and the most potent cytotoxic T lymphocyte (CTL) activity. DC-TCS and DC-ITC inhibited T cell activation but induced a certain extent of CTL activity. Conclusions: These data suggest that DC-TSL is a more potent inducer of antitumor immunity against laryngeal cancer than other antigen-loading strategies using whole tumor cell materials. This strategy provides an alternative approach for DC-based immunotherapy for laryngeal cancer.