Clonal approaches to immune regulation by lymphocytes.

Analysis of immune regulation has been greatly facilitated by the development of clones of antigen reactive T cells. We have been analysing the regulation of these clones both by antigen, and by other cells, and review here the salient features of regulation of helper clones. Antigen at high concentrations may induce tolerance in a helper clone, in the absence of other T cells or accessory cells. This process was markedly antigen dose and time dependent, specific, and lasted at least 7 days. A key features was that response to TCGF was not altered. These experiments indicate that suppressor cells need not be involved in all forms of tolerance, and that antigen can interact directly with T cells. Regulation by an autologous anticlone raised by in vitro immunization of PBL with an irradiated clone is discussed. Its specificity for the immunizing clone suggests that it may recognize receptors, and suppressor clones of this type may be a possible strategy for regulating unwanted clones of lymphoid cells in autoimmunity or leukaemias. The implications of these findings for cancer in general are discussed.