FURTHER STUDIES ON A THYROID STIMULATING FACTOR IN CRUDE CHORIONIC GONADOTROPHIN PREPARATIONS AND IN URINE

Abstract

Urine from pregnant women was concentrated by a kaolin-acetone method and tested by the McKenzie bioassay (1958) for thyrotropin (TSH). Only small responses, without any dose-response curve were found. However, more purified proteins, recovered from an intermediate step in human urinary chorionic gonadotropin (crude HCG) purification and supplied by Organon, Holland, produced much higher biological responses, when tested in corresponding concentrations. Yet, even here, no straight dose-response curve was obtained and the responses were more prolonged at higher concentrations. As described before (Burger 1967), thyroid stimulating factor in purified human urinary chorionic gonadotropin (TSF in HCG) produced a straight dose-response curve. In gel filtration studies, TSF in HCG together with the bulk of urinary proteins were eluted more rapidly than bovine TSH (BTSH), suggesting a higher molecular weight of TSF in HCG preparations. By double diffusion technique, uromucoid could be demonstrated immunologically in crude and in purified HCG. To explain the different biological responses in crude and purified urinary proteins in the McKenzie bioassay and the different elution patterns in gel filtration studies with TSF in HCG and TSH, the following hypothesis is advanced: In urine TSH is bound to urinary proteins, possibly to uromucoid, which interfere with its biological activity. The biological activity is regained by purification.