抗イデイオタイプ抗体を活用したハブテンの高感度イムノメトリックアツセイ

摘要

Noncompetitive immunoenzymometric assays for a hapten molecule employing anti-idiotype antibodies (Ids) are introduced to enable sensitive determination of endogenous steroids in clinical specimens. Ids recognize an epitope in the variable region (idiotope) of anti-hapten antibody (primary antibody); a-type Id (Id-a) recognizes an idiotope in the framework region, while /Hype Id (Id-beta) recognizes an idiotope on the paratope. The target hapten was captured by an excess amount of primary antibody, and the unoccupied paratope was blocked with Id-beta. The hapten-primary antibody complex was selectively detected with bio-tin-labeled Id-a that does not bind to the antibody blocked by Id-beta because of steric hindrance arising by Id-/?. This method was applied to the determination of ursodeoxycholic acid 7-N-acetylglucosamindes, which are bile acid conjugates expected to be diagnostic markers for primary biliary cirrhosis. A similar assay procedure for ll-deoxycortisol(ll-DC), a diagnostic index for pituitary-adrenal function, was also established where the hapten was captured with a biotin-labeled primary antibody and then the complex was captured by immobilized Id-a. These methods were approximately 10 times more sensitive than conventional competitive assays employing the same primary antibody.