Characterization of antisera to the addition product formed by the nonenzymatic reaction of 16 alpha-hydroxyestrone with albumin.

16 alpha-Hydroxyestrone (16 alpha OHE) has been shown previously to react nonenzymatically with proteins via a Heyns rearrangement of a Schiff base intermediate. Albumin modified by the addition of 16 alpha OHE is immunogenic, despite a relatively low molar substitution. High-titre antisera can be elicited which have a very high affinity toward the estrogen hapten. Cross-reactivity analysis reveals a high specificity for the phenolic A-ring and a lack of specificity to chemical substituents in the D-ring, the site of covalent linkage. The antisera reacts equally well with 16 alpha OHE-peptides as with 16 alpha OHE-lysine, suggesting the utility of this antisera in analyzing either enzymatically or chemically hydrolyzed proteins for the presence of 16 alpha OHE adducts. Immunochemical analysis of proteins modified by 16 alpha OHE may provide insight into the pathogenesis of systemic lupus erythematosus, an autoimmune disease in which elevated levels of 16 alpha OHE are known to occur.