Heterologous enzyme immunoassay for serum androstenediol

A heterologous enzyme immunoassay for serum androstenediol (Adiol: 3beta, 17beta-dihydroxy-androst-5-ene) was established. The combination of anti-Adiol antiserum raised in rabbit against Adiol 7-O-(carboxymethyl)oxime (Adiol 7-CMO) conjugated bovine serum albumin (Adiol 7-CMO-BSA) and Adiol 7-iminomethylcarboxylic acid conjugated alkaline phosphatase was used for the assay. The sensitivity of the heterologous assay system was superior to that of a homologous assay system in which an antibody raised in rabbit against Adiol 7-CMO-BSA and enzyme labeled antigen, Adiol 7-CMO conjugated alkaline phosphatase, were used. The minimal amount of Adiol detected was 0.4 ngml(-1) and the measurable range was from 0. 4 to 150 ngml(-1). Intra-assay coefficients of variation (C.V.) were 8.6% (1.52+/-0.13 ngml(-1), mean+/-S.D., n=10) and 6.7% (13.4+/-0.9 ngml(-1), n=10). Inter-assay C.V. were 12.9% (1.63+/-0.21 ngml(-1), n=8) and 11.5% (12.2+/-1.4 ngml(-1), n=8). A linear relation was observed between the serum sample dilution and the Adiol concentration. For recovery study, authentic Adiol was added to serum sample (original concentration: 1.43 ngml(-1)). The calculated final Adiol concentration was 2.99 ngml(-1). The recovery was 98.6% (n=5). The Adiol concentrations in healthy subjects measured by the proposed assay (male: 1.1+/-0.3 ngml(-1) (mean+/-S.D.), range: 0.7-1. 7 ngml(-1), age: 22-50, n=10; female: 0.6+/-0.4 ngml(-1), range: 0. 2-1.6 ngml(-1), age: 23-48, n=20) were consistent with reported values.