A novel approach to the induction of specific cytolytic T cells in vivo.

The induction of specific cytotoxic T lymphocytes (CTL) is one component in the immune response which can effectively protect the host against the progression of many viral infections. CTL are also known to play an important role in immune defence against tumour growth. CTL induction is dependent the presence of the specific antigen, appropriately presented, and interleukin-2 (IL2), provided by T helper lymphocytes. We studied the specific CTL response induced by tumour cells transfected with murine IL2. Our results show that tumour cells manipulated to secrete IL2 induce an improved specific anti-tumour response which results in tumour rejection in mice. To further investigate the effect of IL2 on the CTL response to different antigens, we introduced synthetic peptides into IL2-secreting tumour cells and determined the specific CTL induction in syngeneic mice immunized with these cells. We report here that such IL2-secreting cells can effectively prime peptide-specific CTL in vivo. Our data are relevant to immunotherapy and vaccine development and open up the possibility that autologous cells, manipulated to secrete IL2 and located with one or a cocktail of peptides, could be used to stimulate a specific CTL response.