Structural and serological relationships among different antibodies from the same rabbit antiserum. II. The idiotypes of ten antibody components from an anti-streptococcal serum.

In studies aimed at elucidation of the idiotypic relationships among antibodies produced by a single rabbit, ten antibodies were isolated from the serum of a rabbit immunized with streptococcal Group C vaccine. Four of these antibodies were obtained in amounts sufficient to prepare homologous (rabbit) anti-idiotype antisera. The antisera were used to test for cross-reactivities among all ten antibodies by binding and inhibition of binding assays. Idiotypic cross-reactions among the antibodies were detected by three of the four antisera, while the fourth antiserum reacted only with the antibody that was used as the immunogen for its preparation. Two antibodies demonstrating the highest degree of cross-reactivity had readily distinguishable VH allotypic (a1) subspecificities. The idiotypic reactions and cross-reactions could be inhibited by haptens prepared from the Group C carbohydrate. Bleedings taken from the three immunization periods of this rabbit indicated that the four idiotypes were expressed in approximately equal amounts in each immunization period and that all idiotypes dropped to undetectable levels between immunization periods.