A general method for rendering Δ3-3-oxosteroids antigenic by coupling to a macromolecule through position 7 is described. It involves nucleophilic attack on the 6, 7-dehydroderivatives of the steroids by ambidentate reagents to form 7α-thioether alkanoic acids. These were covalently attached to bovine serum albumin (BSA) by use of the carbodiimide reagent. Addition products with mercapoacetic acid and β-mercaptopropionic acid and their BSA-conjugates, were thus obtained from testosterone androst-4-ene-3, 17-dione, progesterone and 17α-hydroxyprogesterone through the respective 4, 6-dienes.

This chapter discusses the antibodies to oestrogens. It was demonstrated that the attachment of small molecules to protein might lead to the formation of immunogenic macromolecules, capable of eliciting the production of antibodies whose specificity is directed towards the small molecule or “hapten”. Production of specific antibodies to oestrogens helps in the development of radioimmunoassay. The phage inactivation assay procedures were modified; for establishing the role of endogenous oestrogen in ovum implantation in the rat; and for possible medical and veterinary applications. It has been possible to render oestrogens antigenic by coupling them to synthetic macromolecules or protein at sites remote from the hydroxyl functions or the phenolic ring of the hormone molecule, and to devise specific immunoadsorbants to isolate the oestrogen-directed immunoglobulins so produced. These should be useful for the determination of oestrogens by immunoassay. Isoflavone-induced antibodies do not cross-react with oestradiol.