14 Total Lymphoid Irradiation - Induced Suppressor

Studies of adult BALB/c mice given total lymphoid irradiation (TLI; 3,400 rad) 1 have shown that both heterologous proteins and allogeneic bone marrow (BM) cells injected into irradiated mice evoke a state of tolerance rather than immunity (1). The ease of induction of tolerance to protein antigens appears to be related to the development of a population of T cells that can nonspecifically suppress the in vivo adoptive antibody response to the dinitrophenyl (DNP) hapten coupled to heterologous proteins such as bovine serum albumin (BSA) and bovine gammaglobulin (2). Similarly, the initial lack of responsiveness to allogeneic BM cells in TLI-treated mice is related to the presence of T cells that can nonspecifically suppress the mixed leukocyte reaction (MLR) in vitro and graft-vs.-host disease in vivo (3). Our recent work demonstrated the presence of a population of spleen and lymph node cells bearing the thymus-leukemia (TL) surface antigen after TLI (1). ~ The object of the present work was to determine whether these TL + cells are able to suppress the in vivo adoptive antibody response to DNP-BSA, and the in vitro proliferative response to allogeneic stimulator cells (MLR). The results suggest that two subpopulations of suppressor T cells are present in TLI-treated mice: a TL + subpopulation that mediates the suppression of the adoptive antibody response, and a T L subpopulation that mediates the suppression of the MLR.