Specificity of antisera to sex steroid II--effect of unsaturation in ring-B of testosterone.

ABSTRACT

In a testosterone coated tube enzyme immunoassay format, a structurally modified enzyme label 6-dehydrotestosterone-17-hemisuccinate-penicillinase (6-DT) shows lower crossreactivity (25%) towards 5 alpha-dihydrotestosterone (5 alpha-DHT) as compared to testosterone-17-hemisuccinate-penicillinase (45%). The antiserum, generated against testosterone-3-0-carboxymethyloxime-BSA conjugate, showed high crossreactivity with 5 alpha-DHT when evaluated with a RIA (44.8%) using tritiated testosterone tracer. The results suggest that the conformational changes in the new modified testosterone heterologous enzyme tracer (6-DT) brings about desired changes in crossreactivity of antisera against 5 alpha-DHT. The new assay format presents a novel approach to minimize interference due to 5 alpha-DHT crossreactivity in testosterone immunoassays.