Anti-idiotope vaccines: can they exist?

Abstract

Idiotopes and idiotypes are determinants on antibody molecules and lymphocyte receptors which confer a degree of uniqueness to these molecules; a number of the idiotypes are associated with the paratope (antigen-combining site) of the antibody. Since idotypic determinants can be recognized as ‘foreign’ by the autologous immune system, both antibodies and lymphocyte receptors which are anti-idiotypic in function can be found. Hence, anti-idiotype antibodies against paratope-associated idiotypes (Id p) would themselves have paratopes of similar conformation to the epitope on the antigen with which the Id p-bearing antibody reacted. These are the ‘internal image’ anti-idiotype antibodies. Vaccination of animals with such anti-idiotype preparations should result in the production of Id p-bearing antibody molecules. If these Id p antibodies were protective against infection by a particular pathogen, then the anti-idiotope [anti-(Id p)] preparation would be considered a surrogate antigen. Such anti-idiotype surrogate antigens have been identified, but they were polyclonal and their composition is not, as yet, completely understood. Monoclonal ‘internal image’ anti-idiotype antibodies have not proved to be consistently successful surrogate antigens. This may reflect a requirement for a minimum avidity of reaction, and antibody specificities in addition to that of the ‘internal image’. Further insight into the composition of the polyclonal surrogate antigen is required before elaboration on an ‘anti-idiotope vaccine’ can be provided.