Abstract
The preparation and antigenic properties of estradiol 3-glucuronide-bovine serum albumin conjugate in which the hapten is linked to the carrier protein through an (O-carboxymethyl) oxime bridge at the C-6 position on the steroid nucleus, are described. Antiserum elicited in the rabbit by the immunogen possessed high affinity and specificity to estradiol 3-glucuronide, exhibiting hardly any cross-reactivities with other estrogen conjugates except for estrone 3-glucuronide (18.66%) and no cross-reactions with free estrogens and other related steroids. This antiserum was purified by affinity chromatography on estrone 3-glucuronide-aminoethyl cellulose conjugate. The purified antiserum exhibited no cross-reaction with estrone 3-glucuronide. A direct radioimmunoassay method for urinary estradiol 3-glucuronide was developed by using the purified antiserum. The values obtained with the purified antiserum were somewhat lower than those with the native one. The within- and between-assay variations were 3.32 and 4.35%, respectively. The values obtained by the present method correlated closely with those obtained by the established indirect radioimmunoassay (RIA) method.
