Regulation of cytotoxic T-cell reactivity to syngeneic tumors by the thymus.

Adult thymectomy has been shown to result in the enhanced capacity of splenic T cells to respond to and lyse syngeneic tumor cells in vitro. In addition, T cells from thymectomized mice which kill syngeneic tumor cells do not lyse either normal lymphoid or mitogen-stimulated syngeneic lymphoblast target cells. These findings indicate that the thymus exports a subpopulation of T cells sensitive to adult thymectomy which regulates the generation of cytolytic T cells directed against syngeneic tumor cells.