Genetic control of the immune response to the terpolymer L‐glutamic acid⁶⁰‐L‐aIanine³⁰‐L‐tyrosme¹⁰ (GAT): II. Characterization of a cross‐reactive idiotype associated with anti‐GAT antibodies from responder and nonresponder mice

Abstract

Abstract An anti‐idiotypic antiserum specific for the antibodies directed against the terpolymer poly(Glu 60 , Ala 30 , Tyr 10 ), referred to as GAT, has been prepared in rabbit immunized with anti‐GAT antibodies purified from ascites fluid of BALB/c GAT responder mice. The specificity of this serum has been investigated. The interaction between 125 I‐labeled anti‐GAT antibodies and the anti‐idiotypic antiserum is specifically inhibited by anti‐GAT antiserum or anti‐GAT ascites fluid. GAT and the copolymer of L‐glutamic acid 50 ‐L‐tyrosine 50 , but not the closely related copolymer of L‐glutamic acid 60 ‐L‐alanine 40 , inhibit the idiotype‐anti‐idiotype binding indicating a close association of idiotypic determinants with the antibody combining site. This GAT idiotype was found in the anti‐GAT antibodies of all individuals of all inbred strains of mice tested regardless of their allotypic markers. This GAT idiotype has also been found in serum of nonresponder mice immunized with GAT bound to methylated bovine serum albumin. Therefore, the existence of a GAT cross‐reactive idiotype represented in a very large number of inbred strains of mice has been identified. These results are in contrast to results obtained in other experimental systems where linkage was always observed between allotypic and idiotypic specificities.