Infectious and noninfectious tolerance are blocked by a monoclonal antibody to T-suppressor factor

Two forms of hapten-specific unresponsiveness have been demonstrated following intravenous (iv) injection of hapten-conjugated syngeneic spleen cell based on the nature of the antigen-presenting cell (APC): I-J⁺, I-A^- APC have been shown to induce T-suppressor cells (Ts cells) which are demonstrated upon adoptive transfer, while I-J^-, I-A⁺ APC induce a nontransferable tolerance. In this paper we report that a monoclonal antibody specific for T-suppressor effector cells and factors (14-12) can block the Ts cells induced by I-J⁺, I-A^- APCs and the tolerance induced by I-J^-, I-A⁺ APCs. In addition, it sufficiently overcomes suppression such that injection of TNP-spl iv induces immunity rather than suppression. We show that the I-A⁺, I-J^- TNP-spl, which induce nontransferable tolerance upon iv injection, are the cells which induce immunity in 14-12-treated recipients. These results demonstrate that injection of I-J^-, I-A⁺ APC does not lead to clonal deletion and the tolerance induced by the iv injection of both I-J⁺, I-A^- and I-J^-, I-A⁺ APC Operate via Ts Cells.