Immunologic Reaction Between Human Luteinizing Hormones and Antiserum to Urinary Luteinizing Hormone

Abstract

Antiserum was produced in rabbits to a partially purified LH fraction of human postmenopausal gonadotropin (HMG) and then absorbed with human serum and a potent FSH preparation from HMG. The absorbed antiserum appeared to be serologically specific to human urinary LH. This ''antiserum gave no demonstrable precipitin reaction with either a highly purified human pituitary LH preparation or serum gonadotropin, but did inhibit the OAAD [ovarian ascorbic acid depletion] activities of these 2 preparations. Neither precipitation nor neutralization occurred between the antiserum and HCG [human chorionic gonadotropin]. The degree of immunologic cross-reactivity among various human LH preparations was examined by quantitative micro-complement fixation with the absorbed antiserum, and the following values of the immunologic index of dissimilarity were obtained: urinary LH 1.00, serum gonadotropin 3.1, pituitary LH 6.0 and HCG 1.0. Complement-fixing activities of nonpregnant urinary LH preparations were in good agreement with their LH potencies; however, this did not hold true for HCG. The complement fixation reaction of human pituitary LH with the specific antiserum was increased after partial chymotryptic hydrolysis of the pituitary LH. These results would indicate that, although certain differences in the antigenic structure exist between human urinary and pituitary LH, urinary LH may represent a constituent part of the immunologically active core of human pituitary LH.