Effect of beta-3-Thienylalanine on Antibody Synthesis IV. Suppression of the Immune Response in Mice.

The analogue of phenylalanine, beta-3-thienylalanine (beta-3-TA), inhibits the primary and secondary immune responses to sheep red blood cells in CBA mice fed with phenylalanine-free diet. The optimal dose of beta-3-TA needed to obtain maximum immunosuppression with minimal toxicity is 250 mg per kg per day. The drug is maximally effective when administered for 7 days, beginning 2 days prior to primary immunization. With these experimental conditions, the antibody titers and the numbers of direct and indirect plaque-forming cells are greatly reduced during the primary and the secondary immune response.