A MONOCLONAL ANTI‐IDIOTOPE ANTIBODY REACTING WITH A DETERMINANT OF THE CROSS‐REACTIVE IDIOTYPE ON ANTI‐p‐AZOBENZENEARSONATE ANTIBODIES OF A/J MICE

A hybrid cell line, 14A1, was produced that secretes antibodies reacting with a monoclonal A/J anti-p-azobenzenearsonate (ABA) antibody, 7.1.3, previously shown to have all of the determinants of the cross-reactive idiotype (CRI) defined by rabbit anti-idiotype sera. 14A1 were detected using a sensitive assay that is specific for antibodies against idiotypic, but not allotypic nor isotypic, determinants. This was confirmed by demonstrating that 14A1 antibodies bind 7.1.3 but not other A/J monoclonal antibodies of the same class or CRI- monoclonal anti-ABA antibodies. The idiotypic determinant recognized by 14A1 is located at or near the hapten-binding site of 7.1.3, as ABA-conjugated tyrosine is capable of blocking this interaction. RAbbit anti-CRI antibodies are prevented from binding to 7.1.3 by the addition of 14A1, demonstrating the spatial proximity of the 14A1 idiotope with determinant(s) of the CRI. All A/J anti-ABA antibodies that have the 14A1 idiotope are also CRI+, while anti-ABA antibodies from other strains of mice to not express this idiotope. Furthermore, antibodies from A/J mice immunologically suppressed for the CRI also fail to interact with 14A1 antibodies. These results have implications both for the nature of the CRI and for the regulation of the immune response by anti-idiotype antibodies.