Antigen-Specific T Cell-Mediated Suppression

Abstract

The induction of new suppressor T cells (T_s2) by suppressive extracts (T_sF)from L-glutamic acid⁵⁰-L-tyrosine⁵⁰ (GT) nonresponder mice was examined. Incubation of normal spleen cells with allogeneic GT-T_sF for 2 days in vitro led to the generation of T_s2 cells able to suppress subsequent responses to the immunogen GT-methylated bovine serum albumin (GT-MBSA) in vivo. This induction occurred efficiently when T_sF donor and target cells differed at all of H-2, including the I-J subregion. B10.BR (H-2^k) GT-T_sF, adsorbed on, then acid eluted from GT-Sepharose and anti-I-J^k [B10.A (3R) anti-B10.A (5R)]-Sepharose in a sequential fashion could induce BALB/c (H-2^d) spleen cells to become T_s2 only if nanogram quantities of GT were added to the purified GT-T_sF. This indicates a requirement for a molecule or molecular complex possessing both I-J determinants and antigen (GT)-binding specificity, together with GT itself, for T_s2 induction. The induced T_s2 are I-J⁺, since their function can be eliminated by treatment with anti-I-J^k plus C. These I-J determinants are coded for by the precursor of the T_s2 and do not represent passively adsorbed, I-J coded T_sF, since anti-I-J^k antiserum [(3R × DBA/2)F₁ anti-5R] which cannot recognize the BALB/c (I-J^d) T_sF used for induction still eliminates the activity of induced A/J (I-J^k) T_s2. These data provide further evidence for and information about the minimum of two T cells involved in antigen-specific suppressor T cell systems.