Dendritic cells pulsed with apoptotic squamous cell carcinoma have anti-tumor effects when combined with interleukin-2

Objectives: Dendritic cells, the most potent of the antigen-presenting cells, have been widely studied as a promising tool for antitumor immunotherapies. However, little has been determined about the efficacy of dendritic cell-based therapy for the treatment of squamous cell carcinoma (SCC) because there are no known SCC-specific antigens. Recent reports indicate that dendritic cells can acquire antigens in the form of apoptotic cells and induce cytotoxic T-lymphocyte responses. The aim of this study was to test the feasibility of adoptive dendritic cell immunotherapy against SCC by using apoptotic tumor cells as a source of tumor antigens. Study Design: A poorly immunogenic SCC line KLN 205 was used to make subcutaneous tumors on the flank of DBA2/J syngeneic mice. Bone marrow-derived dendritic cells were pulsed with ultraviolet B-irradiated (apoptotic) KLN 205 cells in vitro and transferred to the opposite flank subcutaneously. Some of the animals received simultaneous intraperitoneal injections of low-dose interleukin-2. Results: When combined with interleukin-2, adoptive transfers of dendritic cells that were pulsed with apoptotic SCC significantly suppressed the tumor growth (P <.001) without notable side effects. Splenic T cells of treated mice produced greater amounts of interferon-γ when restimulated with the relevant tumor (P <.001) as compared with control groups, indicative of an effective T-cell-mediated systemic immune response. Conclusion: Adoptive transfer of dendritic cells pulsed with apoptotic tumor cells as a source of tumor antigens, can elicit effective antitumor responses in the poorly immunogenic SCC model when combined with interleukin-2.