Improvement of specificity of anti-testosterone and anti-5 alpha-dihydrotestosterone rabbit antibodies by immunotolerance techniques.

Anti-testosterone (T) and anti-5 alpha-dihydrotestosterone (DHT) antibodies were raised in rabbits after preimmunization with 17 beta-hemisuccinamido, 7 beta-hemiglutaramido- and 3 beta-hemiglutaramido haptens of DHT and T covalently linked to D-glutamic acid-D-lysine (D-GL) copolymer, followed by immunization with the corresponding haptens covalently linked to bovine serum albumin. Preimmunization with DHT-D-GL in the case of anti-T-antibodies or with T-D-GL, in the case of anti-DHT antibodies significantly lowered the T-DHT cross-reactivity in all cases, the most striking effect being observed with anti-17 beta-hemisuccinamido-T antibodies (CR less than 1%). The evolution with time of the binding characteristics was also studied, showing that in several cases the lowered T-DHT cross-reactivity could be maintained after several booster injections until a useful titer was reached. The better results obtained with 17 beta-hemisuccinamido haptens suggest that the structure of the hapten exerts a strong influence on the induction of immunotolerance.