Immunological studies of the luteinizing hormone: II. Comparative study of antigenic compounds

Abstract

Comparison of the antigenic compounds in luteinizing hormone preparations of ovine, bovine, equine, and human origin was made using a hyperimmune rabbit antiserum to ovine luteinizing hormone. Methods involving agar double diffusion and immunoelectrophoresis revealed more precipitin lines in the ovine and bovine preparations than in those of either human or equine origin. The lines of the ovine and bovine hormones were fairly well balanced in electrophoretic mobility and similar to each other in appearance, whereas the lines of the equine and human hormones were predominantly anodic and differed in appearance from those of ovine and bovine preparations. The hemagglutination inhibition method showed that larger quantities of human and equine hormones than of ovine and bovine hormones were needed to inhibit the interaction between the hyperimmune antiserum and its homologous hormone. There was no correlation between the results of these tests and biological potency. Contamination with follicle-stimulating hormone was demonstrated by immunoprecipitation tests in all five hormone preparations, suggesting a lack of species specificity for this hormone and pointing to the clear antigenic dissimilarity between luteinizing and follicle stimulating hormones. Contamination with thyroid-stimulating hormone was demonstrated serologically only in the extracts of ovine and bovine glands. The ovine, bovine, and equine preparations of luteinizing hormone contained antigenic components which overlapped 3 3 An overlapping component is defined as a component certain antigenic determinants of which are shared by another hormone. with pregnant mare's serum gonadotropin, and the existence of a component in ovine, bovine, and human extracts which overlapped with human chorionic gonadotropin was also established.