Suppressor T cell circuits in contact sensitivity. I. Two mechanistically distinct waves of suppressor T cells occur in mice tolerized with syngeneic DNP-modified lymphoid cells.

Suppressor T cells induced by the i.v. injection of syngeneic DNP-LC were studied at varying times after tolerization. It was found that 7 days after tolerization both the spleen and lymph nodes of tolerant mice contained Ts active in suppressing the efferent (effector) phase of the contact sensitivity response (Ts-eff). At 14 days after tolerization, however, only the spleen showed significant suppressive activity that was active on the afferent (induction) phase of the contact sensitivity response. This second wave of afferent suppression was shown to be mediated by an antigen-specific, Ia-positive T cell (Ts-aff). Ts-aff could also be induced in normal, but not in CY-pretreated mice transfused with lymphoid cells containing primed Ts-eff, provided an appropriate induction period was allowed. Also the activity of Ts-aff, but not of Ts-eff, could be eliminated by treatment with anti-DNP antibody (i.e., idiotype) and C. Thus, Ts-aff appears not to be a maturation stage of Ts-eff. It was also shown that Ts-eff and Ts-aff interacted in an antagonistic fashion; cotransfer of these populations along with DNFB-immune TDH cells neutralized the efferent suppressive activity of Ts-eff for the immune cells, allowing successful passive transfer of immunity. The exact role of this antagonistic interaction is not clear, but it may play a part in maintaining the balance of suppression in the intact animal. The data are discussed in terms of a cellular network in immune suppression and are compared and contrasted to other suppressor systems in which network interactions have been described.