The effects of antisera directed against various human glycoprotein hormone subunits on the biologic activity of human pituitary thyrotropin (hTSH), human chorionic thyrotropin (hCT), bovine pituitary thyrotropin (bTSH1), and long-acting thyroid stimulator (LATS) were studied. Relative thyroid-stimulating potencies were determined using a McKenzie mouse assay. Antiserum to the human chorionic gonadotropin a-subunit (hCGα) completely neutralized hTSH but not hCT, bTSH, or LATS. Antisera to the hCG β-subunit (hCGβ) only partially neutralized hTSH and had no inhibiting effect on the biologic activity of hCT, hTSH, and LATS. In contrast, antisera to the human luteinizing hormone β-subunit had no significant effect on hTSH biologic activity. These results confirm previous reports indicating common antigenic determinants on hCGα subunit and hTSH and suggest similarity of the a subunits of hCG and hTSH. Placental thyroid-stimulating activity was not neutralized by either anti-hCGα or anti-hCGβ sera, indicating that hCT is immunologically distinct from hTSH and hCG, and suggesting that hCT does not have an α-subunit structure immunologically similar to that in the other human glycoprotein hormones.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Clinical Biochemistry
- Biochemistry, medical