When the skin of Tg.Con.3-1 transgenic mice expressing the TL (thymus
leukemia)
antigen in most tissues is grafted on syngeneic C3H mice, it is rejected, and a cytotoxic T cell (CTL) response against the
TL antigen is induced. In this study, we first demonstrated that growth of TL positive
lymphoma is suppressed in mice immunized by
skin grafting. Immunization with bone marrow derived dendritic cells (DCs) from Tg.Con.3-1, was also found to be associated with an anti-
tumor response, but less potent than
skin grafting. Relative CTL precursor frequency with DC immunization was also approximately only one third that of
skin grafting. The numbers of IFN-gamma producing cells in responder CD8 and CD4 T cell populations were higher with DC immunization than with
skin grafting. However, DC immunization seems to induce non-specific immune responses, as re-stimulation with TL negative C3H spleen cells resulted in induction of almost half the number observed with TL positive cells. Thus, the actual number of IFN-gamma producing cells in specific responses to TL is not necessarily larger than with
skin grafting immunization. The present results altogether suggest that DC immunization is capable of inducing an anti-
tumor reaction, but also possibly unwanted immune responses. In vitro monitoring of specific and non-specific responses in the immune system, thus, is of particular importance for future development of
cancer immunotherapy.