Immunosuppressive factor(s) specific for L glutamic acid⁵⁰ L tyrosine⁵⁰ (GT). I. Production, characterization, and lack of H-2 restriction for activity in recipient strain

The random synthetic copolymer of L glutamic acid⁵⁰ L tyrosine⁵⁰ (GT) fails to elicit a GT specific antibody response in all inbred strains of mice tested. Preimmunization with GT specifically inhibits a GT methylated bovine serum albumin (MBSA) response in certain, H 2(d,k,s), but not other, H 2(a,b,q), nonresponder mice. This unresponsiveness is mediated by GT specific suppressor T cells. Extracts prepared from lymphoid cells of GT primed suppressor haplotype mice inhibit the development of primary GT specific antibody responses to GT MBSA in normal syngeneic mice. Nonsuppressor haplotype mice do not produce GT specific suppressor factor. The GT suppressive extract has affinity for antigen and a m.w. of less than 50,000 daltons, thus, resembling antigen specific immunosuppressive factors already described. However, the GT suppressive extract does not appear to have H 2 restrictions since it works across allogeneic barriers. Evidence is presented that 2 genes are required for factor mediated suppression.