Immunologic Studies of Anti-Gonadotropic Sera

Abstract

We have reported 1 , 2 that the serum of rats and rabbits treated with anterior-pituitary-like hormone (A.P.L.) of pregnancy urine contained substances capable of protecting test animals against the gonadotropic action of this hormone. The A.P.L. used in these experiments was prepared by alcohol-salt precipitation methods and consequently contained nitrogenous substances giving some of the reactions common to antigenic proteins. It was of interest, therefore, to determine whether the A.P.L.-inhibitory sera of treated animals contained antibodies against A.P.L. in the immunological sense.

For this purpose 4 preparations of A.P.L. from different collections of pregnancy urine and one control product prepared by identical methods from male urine were examined. The gonadotropic potency of the pregnancy urine extracts varied between 10 and 100 rat-day-units (R.D.U.) per milligram of dry substance, the differences being accounted for principally by variations in salt content of the preparations. The male urine extract possessed no gonadotropic properties, but like the pregnancy urine extracts, gave the biuret and Millon reactions.

Each of the above preparations was injected intravenously into 5 female rabbits. The A.P.L. treated rabbits received 5 daily increasing doses of from 100 to 1000 R.D.U. in salt solution, and following a rest period of 5 days, a second course of from 500 to 2500 R.D.U. The rabbits treated with male urine extract received similar courses of injections in doses ranging from 10 to 150 mg. of dry substance dissolved in salt solution. The animals were bled from the fourth to the tenth day following the last injection. As previously reported, the serum of rabbits treated with A.P.L. in this manner was highly potent in A.P.L.-inhibitory substance.