In vitro analysis of T cell responses induced by breast tumor cell lysate pulsed with autologous dendritic cells

In this in vitro study, T cell responses induced by breast tumor cell lysate pulsed monocyte-derived DCs were analyzed in terms of proliferation, specific cytotoxicity and cytokine-release in order to use in immunotherapeutic settings. Nylon wool enriched T lymphocytes from 5 patients with breast cancer stimulated in vitro with tumor cell lysate pulsed monocyte-derived DCs and their proliferation response were analyzed by [H] thymidine uptake test. Specific cytotoxic activity of tumor antigen primed T cells after three rounds weekly stimulation was evaluated by flow cytometry, and interferon-γ (IFN-γ) and interleukin-4 (IL-4) cytokines release assay was carried out 24 hours after last stimulation in the supernatant of primed T cells using commercially available ELISA kits. T cell proliferation assay revealed that tumor cell lysate pulsed DCs could stimulate autologous T cell proliferation response with stimulation indices 4.9 30. T cell mediated cytotoxicity assay demonstrated that tumor antigen primed T cells could significantly kill autologous tumor cells more than normal cells (P < 0.05). These cells had variable amounts of cytotoxic activity against K562 cells as well. Primed T cells were released both IFN-γ and IL-4 in response to restimulation by antigen pulsed DCs which were dominated by IFN-γ production in 2 and IL-4 production in 3 out of 5 patients. Our result suggested that breast tumor antigen pulsed DCs could elicit effective specific antitumor T cell responses in vitro, therefore, tumor antigen pulsed DC vaccination may be considered as a novel strategy for immunotherapy of patients with breast cancer refractory to standard modalities.