STUDIES ON A HUMAN CHORIONIC GONADOTROPHIN-LIKE MATERIAL PRESENT IN NON-PREGNANT SUBJECTS

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Abstract
The presence of a hCG[human chorionic gonadotropin]-like material in urinary and pituitary extracts and plasma obtained from non-pregnant subjects and investigated. Two assay methods were used to detect this material following fractionation of pituitary and urinary extracts by gel filtration (Ultrogel AcA 54) and/or isoelectrofocusing: a radioimmunoassay employing an antiserum raised against a specific sequence of the carboxy terminal region (residues 115-145) of the .beta.-subunit of hCG and an in vitro bioassay method which measures both hLH [human lutropin] and hCG activities. The fractionation procedures employed provide a satisfactory separation of highly purified hCG and hLH preparations. In the pituitary and urinary extracts hCG.beta.-peptide-like immunoactive (PIA) material was found consistently, which co-eluted with iodinated hCG following gel filtration and possessed pI [isoelectric point] values similar to those of hCG when subjected to isoelectrofocusing. The PIA material also exhibited in vitro biological activity similar to that shown by hLH and hCG. Detectable levels of immunoactive material were also found in plasma; the plasma levels of this PIA material were not influenced by classical endocrine measures such as the stimulation or inhibition of gonadotropin secretion. The low levels of this material in plasma precluded its further characterization by gel filtration or electrofocusing. Although the presence of some hCG-like material in urinary and pituitary extracts and possibly in plasma of non-pregnant subjects is suggested, the available evidence is not sufficiently conclusive to exclude other interpretations as to the nature of this material.