Specific antisera for the radioimmunoassay of estriol 3-sulfate

Antisera were raised in male guinea pigs against 6-oxoestriol 3-sulfate O-carboxymethyloxime-bovine serum albumin (BSA) conjugate. The antisera to this antigen exhibited high affinity (Ka=4.7 X 10(9)M-1) and excellent specificity for estriol 3-sulfate, showing slight cross-reactions (less than 0.43%) with other estrogen sulfates, and no cross-reactivities with free estrogens and other steroids (less than 0.01%) except cholesterol sulfate (0.22%). A standard curve using [6, 7-3H]-estriol 3-sulfate as the radioactive ligand showed high sensitivity in the range of 10-1000 pg estriol 3-sulfate.