Immunologic Inhibition of Endogenous or Exogenous Thyrotropin in Various Species.

Summary A modification of the Querido bio-assay for thyrotropin is presented along with log dose-response curves for USP Reference Standard Thyrotropin in 2 different strains of mice. The immimobiologic effects of antisera to bovine thyrotropin (TSH) on either endogenous or exogenous TSH were determined in guinea pigs, intact or hypophysectomized rats and mice. In thyroxinized guinea pigs and thyroxinized intact or hypophysectomized rats, passively administered rabbit antiserum to bovine TSH neutralized the biologic activity of exogenous bovine TSH. Rabbit antiserum passively administered to guinea pigs, rats or mice inhibited the effects of propylthiouracil (PTU) on goitrogenesis and on radioactive iodine uptake, indicating biologic neutralization of endogenous TSH in these species. These findings suggest a molecular similarity of guinea pig, rat and mouse thyrotropin.