Effector functions and specificities of normal murine T cells stimulated by syngeneic blasts.

Large numbers of syngeneically stimulated T cells are easily obtained by stimulation of splenic T cell populations with irradiated lipopolysaccharide (LPS) blasts. Thus, proliferative T cell responses were obtained after stimulation with allogeneic LPS blasts, concanavalin A (Con A) blasts, normal spleen cells or peritoneal macrophages while only LPS and Con A blasts were competent syngeneic stimulators. The cytolytic activity of T cells stimulated with allogeneic LPS blasts was H-2 specific, while that of T cells stimulated with syngeneic LPS blasts was often completely nonspecific, and higher for LPS than for Con A blast target cells. In other experiments, "self" H-2K- and I-A-specific cytotoxic T cells were obtained, without apparent reasons for the development of either type of cytolytic cells. Stimulation of Lyt-2- T cells with syngeneic LPS blasts led to the generation of T helper effector cells which induced normal B cell proliferation in an H-2 restricted manner. This restriction was over-come, the proliferative responses were augmented and plaque-forming cell responses generated, through addition of Con A to the cultures. The results imply the ability of B blasts to induce stimulation of syngeneic T cells, and generation of effector cells displaying cytolytic and helper activity. This phenomenon might play a role in the regulation of the immune system.