Anti-immunoglobulins and their idiotypes: are they part of the immune network?

The anti-gamma globulins represent a very heterogeneous group of proteins with widely different specificities that might be considered a portion of the immune network. The hypothesis is presented that at least some of these proteins have other specificities, with the anti-gamma globulin reactivity being a secondary property. Anti-idiotypic antibodies are possible candidates. This is based on the low binding affinity for gamma globulin of many of these proteins and the results of CRI and sequence studies. All the proteins of the major CRI group have VKIIIb light chains, and these have a dominant but not total influence on this CRI. This has been evident from studies with rabbit antibodies and recently also with monoclonal hybridoma antibodies. Sequence studies have also demonstrated the similarity in light chains that, however, are not greater than with other VKIIIb chains; the heavy chains show little similarity except possibly in the J segment. The possibility is discussed that antibodies with secondary anti-gamma globulin binding properties might have selective advantages.