Anti-idiotypes to monoclonal anti-H-2 antibodies—I. Contribution of isolated heavy and light chains to idiotype expression

Abstract

Anti-idiotypic sera were produced by immunization of miniature swine with affinity-purified monoclonal anti-H-2K k antibodies. The purified anti-idiotypic antibodies obtained by this immunization recognized unique determinants on each monoclonal anti-H-2K k immunogen and were not broadly cross-reactive with other anti-H-2K k antibodies. These reagents were used to examine the expression of idiotype on isolated heavy and light chains as well as on reassociated Ig molecules. Minor populations of idiotope(s) could be detected by a direct binding radioimmune assay on isolated heavy chains and on isolated light chains. However, the predominant idiotope(s) were expressed only on native Ig and on isolated heavy chains. The expression of these heavy-chain idiotopes was found to be specifically augmented by the addition of homologous light chains. In contrast, reassociation of heavy chains with light chains from a different anti-H-2K k monoclonal antibody diminished idiotype expression. A model for the molecular interactions occurring between these molecules is proposed on the basis of these results. The nature of these interactions may also have implications for the analysis of the basis of idiotype expression on anti-MHC T-cell receptors.