Induction of th1 response by dendritic cells pulsed with autologous melanoma apoptotic bodies

Background: We hypothesize that dendritic cells (DCs) can process antigens from autologous melanoma apoptotic bodies (MABs) and induce effector T cells in melanoma patients. Materials and Methods: Peripheral blood mononuclear cells were obtained from three stage IV melanoma patients and adherent cells were cultured in complete medium (CM) containing GM-CSF (800 U/ml) and IL-4 (1000 U/ml) for 7 days. Autologous MABs from melanoma cells following actinomycin D treatment (0.5 μg/ml) for 24 hours, were added to 72 hour DC culture. Autologous effector T cells were cultured in CM containing 60 IU/ml of IL-2 and were stimulated by MAB-pulsed DCs three times at a weekly interval Effector T cells were harvested at the end of third cycle of DC stimulation. Results: Using ELISPOT, IFN-γ production by effector T cells stimulated by MAB-pulsed DCs was significantly higher than that by T cells without DC stimulation. Microscopy demonstrated phagocytosis of MABs by DCs. Conclusions: MAB-pulsed DCs are capable of stimulating Th1-directed autologous effector T cells. Pulsing DCs with autologous MABs may be a novel approach in future DC-based immunotherapeutic trials.