Possible cellular events in leukemia.

An immunologically unresponsive state induced in experimental animals can be modulated by a number of procedures. Such modulation can result in the termination of the unresponsive state if there exists a normal complement of immunocompetent B cells in the presence of unresponsive T cells. It is possible to bypass the T cells and activate the B cells to respond to otherwise tolerated antigens. The bypass results from supplying a second (nonspecific) signal to the B cells, which, in the presence of antigen (specific signal), permits the B cell to differentiate. The role of the T and B cells and their activation and/or inactivation in the fate of both leukemic cells and oncogenic viruses is discussed.