| Abstract: | Anti-idiotypic sera which precipitate the anti-Salmonella abortus-equi (Sae) serum used for their preparation (homologous reactions) sometimes precipitate anti-Sae sera other than the one used for their preparation (heterologous reactions). The frequency of these heterologous reactions is about 3 % for 5036 studied reactions. We have detected heterologous idiotypes in several different individuals, which apparently were not distinguished from homologous ones in the reaction in gel medium with the same anti-idiotypic serum. However, the quantity of heterologous anti-Sae serum necessary for inhibiting the homologous reaction is always larger than that necessary for inhibiting the heterologous reaction observed with the same anti-idiotypic serum. Homologous and heterologous reactions indicate that antibodies produced by rabbits submitted to the same anti-idiotypic immunization were sometimes directed against different idiotypes and even against different idiotypic determinants of the same idiotype. We have separated two different IgG idiotypes by the isoelectrofocusing technique. These two idiotypes seem to have different idiotypic specificities. |
