We have demonstrated by using a combination of in vivo priming and in vitro incubation that the injection into mice of cultured cells can lead to the development of cytolytic T cells as a function of the serum used for growing the injected cells. Moreover, mere injection of xenogeneic serum followed by in vitro incubation of the primed cells in serum-containing medium led to the development of cytolytic T cells. The induction and the cytolysis phases of this system had distinct characteristics. For the induction of the development of cytolytic cells, cytophilic xenogeneic serum determinants were necessary and were recognized in a specific way. For cytolysis, T cells were required, which recognized unidentified antigens (but apparently not xenogeneic serum determinants) at the surface of syngeneic or allogeneic target cells. In addition, different strains of mice had different patterns of reactivity in this system.
These results are discussed from two points of view. First, they lead us to issue a serious caveat for the interpretation of experiments done in “syngeneic” conditions, when the sensitizing cells have been in contact with xenogeneic serum. Second, we underline the interest of this system for further studies on the induction of T cell-mediated cytolysis.
This work was supported by the Institut National de la Santé et de la Recherche Médicale, the Centre National de la Recherche Scientifique, and the Délégation Générale à la Recherche Scientifique et Technique (Grant 76.7.0966).