Lysis of inducer T cell clones by activated macrophages and macrophage-like cell lines.

We describe a sequence of reciprocal interactions between cloned inducer T cells and antigen-presenting cells (APC) that results in selective depletion of the antigen-reactive inducer cells. We show that corecognition of antigen and I-A by hapten-reactive inducer T cell clones results in (a) release of macrophage-activating factor (MAF) and other lymphokines, (b) expression of lytic activity by a subset of MAF-sensitized APC after triggering, and (3) lysis (mediated by the activated and triggered macrophage) of the inducer T cell clone and other cells in the vicinity. We suggest that this sequence of steps may limit the extent of macrophage-mediated tissue destruction by depleting the specific inducer T cell clones that initiate the response.