Abstract
Conventional hapten immunoassays are dependent on the competitive reaction between unlabeled antigen (analyte) and labeled-antigen against a limited amount of antibody. Although noncompetitive immunoassay procedures such as two-site immunometric assays offer much higher sensitivity (attomole ?? zeptomole order) and a wider working range, this principle has not been suitable for measuring haptens. We attempted to generate monoclonal anti-idiotype and anti-metatype antibodies which may enable noncompetitive hapten immunoassays with excellent sensitivity, and succeeded in producing α-type and β-type anti-idiotype antibodies, each recognizing the framework region and paratope of a monoclonal antibody against ursodeoxycholic acid 7-N-acetylglucosaminide (UDCA 7-NAG). The combined use of the α-type and β-type antibodies together with the anti-hapten antibody provided a noncompetitive assay system for UDCA 7-NAG, whose detection limit was ca. 500 fg.
