Identification and characterization of a hapten-modifiable TEPC 15 cross-reactive idiotype in swine.

Rabbits and swine immunized with TEPC 15 IgA, goats immunized with T15-positive IgM and swine immunized with affinity-pure swine anti-phosphorylcholine (PC) all produce antibodies which recognize a hapten-inhibitable idiotypic determinant on swine anti-PC. The similarity in reactivity and order of inhibitability with various PC analogs of the heterologous (swine anti-TEPC 15) and isologous (swine anti-swine anti-PC) reagents indicates that they recognize a related idiotype and suggest it may be the predominant idiotype expressed on swine anti-PC antibodies. The heterologous and isologous anti-idiotypic reagents generated in this study recognize swine and mouse anti-PC but not normal swine IgM, IgG or MOPC 460. Only reactions with swine anti-PC and mouse T15-positive anti-PC proteins are hapten-inhibitable. The greater inhibitory capacity of trimethylammonium and acetylcholine than PC suggests that the idiotope(s) recognized on swine anti-PC by the anti-idiotypic reagents is integral rather than peripheral to the anti-PC binding site. The nearly exclusive IgM anti-PC response of swine to Streptococcus pneumoniae R36A and PC-Brucella have so far hindered attempts to study the isotypic distribution of the idiotype.