Analysis of the Cross-Reactive Immune Suppression Induced by the Random Copolymers L-Glutamic Acid⁵⁰-L-Tyrosine⁵⁰ (GT), L-Glutamic Acid⁶⁰-L-Alanine⁴⁰ (GA), and L-Glutamic Acid⁶⁰-L-Alanine³⁰-L-Tyrosine¹⁰ (GAT)¹

Cross-reactivity in the induction of immune suppression by the structurally related polymers of L-glutamic acid, L-alanine, and/or L-tyrosine (GAT, GA, GT) was studied. SJL (H-2^s) and DBA/1 (H-2^q) mice are nonresponders to GAT and GT, whereas SJL, but not DBA/1 responds to GA. Both strains respond to these polymers when complexed to the immunogenic carrier methylated bovine serum albumin (MBSA). Preimmunization with GA suppresses GA-MBSA as well as GAT-MBSA and GT-MBSA plaque-forming cell (PFC) responses in DBA/1 mice. Likewise, GAT suppresses GAT-MBSA and GA (SJL) and GA-MBSA (DBA/1) PFC responses in both strains while being totally ineffective on GT-MBSA responses. GT preimmunization suppressed GA, GAT-MBSA, and GT-MBSA PFC responses in SJL but not DBA/1 responses. This study demonstrates that cross-reactive immune suppression does not follow predictable patterns based upon cross-reactivity of specific antibodies and that cross-suppression is not reciprocal.