Substantial Amounts of Gonadotrophin-Like Materials in Sera of Normal Subjects

Abstract

Ultrafiltration of human sera resulted in increased levels of human chorionic gonadotrophin (hCH), LH and FSH measured by radioimmunoassay. The effect was greatly enhanced by chromatography of serum through Sepharose-protein A (which specifically binds immunoglobulin G) followed by ultrafiltration of the unretarded fractions. Serum from a normally menstruating women was treated by ultrafiltration and the retained fraction from 200 mul serum further chromatographed on a Sephadex G-150 Superfine column. The amounts of LH and FSH measured in the eluate by radioimmunoassay were higher by three orders of magnitude than those found in the untreated serum. Comparable amounts of hCG were also found in the eluate by two specific radioimmunoassays, and a value of 45 i.u. hCG was recovered in the eluate by bioassay. Serum from another normally menstruating women was applied to DEAE-cellulose and eluted stepwise using an elution gradient. The ultrafiltrate of one eluted fraction led to separation of a low molecular weight material which was able to neutralize the biological activity of a large dose of hCG. The data support the hypothesis that substantial amounts of gonadotrophins are normally present in serum but that binding to inhibitor(s) prevents their assay in untreated sera.