Active immunization with estradiol-17beta bovine serum albumin in monkeys.

Active immunization with estradiol-17beta bovine serum albumin (BSA) in monkeys is described. 2 female rhesus monkeys (Maccaca mulata) received 6 weekly injections of 1.5 mg estradiol-17beta-succinyl-BSA as the antigen 4 weekly injections a month later then a monthly booster; 2 monkeys received 3 mg of the same compound in 4 weekly injections plus monthly boosters; and 2 received only saline and Freunds adjuvant. The sera were tested for antibodies by using the principle of the radioimmunoassay for estradiol. Progesterone and its 20-reduced and 17-hydroxylated forms were measured by competitive protein-binding. The 2 monkeys that received 1.5 mg had antibody titers below 10% 3 weeks after the 1st series of injections. A maximum of 33% and 43% within 10 days after the 4th weekly injection was seen. While no antibodies were demonstrable at the beginning of the 2nd series of injections a clear maximum in the assay at a dilution of 1:100 was obtained as the 2nd series progressed and 5 months later the greatest binging at 1:100 (57%) showed some residual binding (24%) at dilutions as high as 1:50000. 1 monkey receiving 3 mg reached antibody titer levels of over 50% after the 1st booster while the other had not produced any antibodies at the time of the 2nd booster. The animals that produced antibodies to estradiol became anovulatory (revealed by serum progesterone or progestin levels) with irregular menstrual cycles. Vaginal cornification with a decrease in parabasal cells was seen in the immunized animals. These results indicate that the absence of ovulatory luteinizing hormone (LH) surges in the immunized monkeys was due to inactivation of the serum estrogens which control the LH surge.