Idiotypic Analysis of Anti-GAT Antibodies

Abstract

Abstract The specificity and distribution of an interspecties cross-reactive idiotype are described in 13 inbred strains of rats. This interspecies cross-reactive idiotype was defined by the ability of rat anti-GAT antisera to inhibit the binding of the murine CGAT idiotype to the corresponding anti-CGAT idiotypic antiserum. High levels of the interspecies cross-reactive idiotype were detected in 9 of 13 rat strains; all individuals of these 9 strains produced detectable levels of the idiotype. The idiotype was always associated with anti-GAT antibodies. Following immunization with GAT, all individuals of the other four rat strains produced anti-GAT antibodies with low or undetectable levels of the interspecies cross-reactive idiotype, although the anti-GAT antibodies from these latter strains had fine specificity patterns similar to that of the idiotype-positive strains. Immunization of the low idiotype producer LEW and F344 strains with GAT conjugated to the highly immunogenic fowl γ-globulin carrier also failed to induce detectable levels of the interspecies cross-reactive idiotype. Prolonged immunization schedules were used to determine the persistence of this idiotype in rats; the data demonstrated that the ability (or inability) to produce the interspecies cross-reactive idiotype is a stable trait and lasts over 174 days. There was no apparent association of the idiotypic marker with the known rat immunoglobulin heavy and light chain allotypic specificities. Finally, the rat interspecies idiotype is cross-reactive, but not identical with the mouse CGAT idiotype.