Idiotypic Analysis of Anti-GAT Antibodies

Abstract Previous studies demonstrated that anti-GAT antibodies of all inbred strains of mice share a common idiotype, termed CGAT idiotype. The CGAT idiotype is present on a major fraction of anti-GAT antibodies and is induced by the “GT”-related antigenic determinants on GAT molecules. The present paper describes another common idiotype of anti-GAT antibodies, termed GA-1 idiotype, the identification of which is based on a heterologous idiotypic interaction between guinea pig anti-idiotypic antiserum made against pooled specifically purified D1.LP anti-GAT antibodies and a monoclonal hybridoma anti-GAT antibody from the F9-102.2 cell line. The homologous anti-F9-102.2 idiotypic antiserum detected private idiotypic specificities. GA-1 and CGAT are distinct idiotypes induced upon GAT immunization. Unlike CGAT idiotype, GA-1 idiotype is expressed on a minor fraction of the anti-GAT antibodies and “GA”-related antigenic determinants are responsible for the inducation of GA-1 idiotype. Thus, anti-GA, anti-GAT and anti-GLA40 antisera from 21 different inbred strains of mice expressed GA-1 idiotype. However, both the CE/J anti-GAT and anti-GA antisera lack detectable levels of GA-1 idiotype.