Failure of Long-Acting Thyroid Stimulator Globulin (LATS) and Serum To Stimulate Thyroid Function in the Chick

Abstract

In the guinea pig and mouse thyrotropin (TSH) bio-assay, an abnormal longacting thyroid-stimulating response to sera from hyperthyroid patients has been noted when compared to bovine TSH Reference Standard. In other species used for TSH bio-assay (chick, stasis tadpole) in which different protocols than those of the mammalian assay animals were utilized, data have been interpreted as showing a lack of LATS response. Utilizing a chick TSH bio-assay with a protocol similar to that of the mouse LATS assay (intravenous injection of testsample), 3 sera obtained from hyperthyroid patients and a γ-globulin fraction of one, all known to have a LATS response in the mouse, were investigated for early TSH-like and LATS responses. lthough the samples were injected at evels up to 30-fold that giving a response in the ouse, no thyroid-stimulating effects were noted t 3, 7 or 18 hr. These data indicate specificity of the chick assay for pituitary TSH and also that LATS responses may be observed only in mammalian assay species. (Endocrinology80: 369, 1967)