Sharing of idiotypic specificities between different antibody populations from an individual rabbit.

Rabbits hyperimmunized with tobacco mosaic virus synthesize very heterogeneous antibodies. Despite this, specific anti-idiotypic sera recognizing a large part (70%) of these antibodies can be raised in rabbits matched for allotypic specificities a1, a2, a3, b4, b5, b6, c7, and b9. Different rabbits synthesize antibodies with different idiotypic specificities. However, in the serum of a single rabbit antibody fractions of different isoelectric pH share some idiotypic specificities. The results show that, at least in certain cases, antibodies against one antigen are not simply a random collection of immunoglobulin which happen to fit with this antigen, but that some definite relationship exists between the products of different clones which have been activated by antigen. These findings are discussed in the light of network concepts of the immune system.