A role for self-recognizing T cells in the regulation of antibody-forming and cell-mediated cytotoxic responses in the mouse.

Mitogen- or antigen-activated murine spleen and thymus cell blasts have been used as inducer cells to stimulate production of suppressor T cells (Ts) in autologous mixed leucocyte culture. Ts cells were induced in an MHC-restricted fashion and produced suppression of cell-mediated lympholysis and antibody synthesis from fresh spleen cells sharing MHC haplotypes with the Ts pool. Ts were Thy 1+, Lyt 1+ cells. Induction of Ts depended upon expression of class II MHC antigens on stimulating cells, but the level of Ts induced by different populations of suppressor inducer cells was not correlated with the level of Ia antigen expression. Activity of suppressor inducer cells was correlated with the functional activity of the inducer pool. The data are interpreted to favour a model in which Ts are induced by associative recognition on stimulator cells of class II MHC antigens and lymphocyte recognition receptors as nominal antigen (i.e. Ts are auto anti-idiotypic in nature). Using as stimulator/responder cells in AMLR lymphocytes taken from normal (8-week) or aged (greater than 24-month) mice, data were obtained consistent with this model and with earlier evidence for an altered expression of both lymphocyte recognition receptors and/or class II antigens in senescence.