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Physiological Studies of Human Chorionic Gonadotropin (hCG), αhCG, and βhCG as Measured by Specific Monoclonal Immunoradiometric Assays

Physiological Studies of Human Chorionic Gonadotropin (hCG), αhCG, and βhCG as Measured by... Abstract Several libraries of monoclonal antibodies have been produced against epitopes that reside on hCG, αhCG, and. βhCG. Having characterized them physically, we explored their use in the construction of highly specific and sensitive immunoradiometric assays. There were several important immunochemical considerations with respect to developing assays that accurately detect low levels of free subunits in serum in the presence of high concentrations of the native hormone. These include physical properties and specificities of the monoclonal antibodies, choice of capture antibody on the solid phase support, assay design, and purity of hormone standards. Using such assays, we found early pregnancy (in vitro fertilization) to be characterized by the sequential appearance of hCG, followed by phCG and then cvhCG. Molar ratios of βhCG to βhCG and βhCG to hCG were highest in early gestation. However, there was a reversal of the βhCG to ahCG ratio at 12–13 weeks gestation, and an excess of free ahCG was observed thereafter. Except for values obtained in very early pregnancy, the βhCG to hCG ratio remained remarkably constant at approximately 0.5% throughout gestation. In contrast, choriocarcinoma was distinguished by absolute serum βhCG concentrations 3–100 times greater than the maximum values observed during pregnancy and, more importantly, by exceedingly high βhCG to hCG ratios. For comparison, we studied hCG, ahCG, and βhCG levels in an additional 178 patients with nontrophoblastic tumors. Ectopic production of αhCG and βhCG was rare (3%), and thus far, we have been unable to demonstrate the presence of hCG in such patients. Therefore, hCG and the free subunits appear not to be useful as serological markers for nontrophoblastic tumors. (Endocrinology120: 549–558, 1987) This content is only available as a PDF. Author notes * This work was supported in part by NIH Grants AA-20666, HD-20469, and CA-35711 and a grant from Association pour la Recherche sur le Cancer (Villejuif, France). † Recipient of a research fellowship from Association pour la Recherche sur le Cancer. ‡ Recipient of Research Center Scientist Development Award AA-00048 from the NIH. Copyright © 1987 by The Endocrine Society http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Endocrinology Oxford University Press

Physiological Studies of Human Chorionic Gonadotropin (hCG), αhCG, and βhCG as Measured by Specific Monoclonal Immunoradiometric Assays

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Publisher
Oxford University Press
Copyright
Copyright © 2021 Endocrine Society
ISSN
0013-7227
eISSN
1945-7170
DOI
10.1210/endo-120-2-549
Publisher site
See Article on Publisher Site

Abstract

Abstract Several libraries of monoclonal antibodies have been produced against epitopes that reside on hCG, αhCG, and. βhCG. Having characterized them physically, we explored their use in the construction of highly specific and sensitive immunoradiometric assays. There were several important immunochemical considerations with respect to developing assays that accurately detect low levels of free subunits in serum in the presence of high concentrations of the native hormone. These include physical properties and specificities of the monoclonal antibodies, choice of capture antibody on the solid phase support, assay design, and purity of hormone standards. Using such assays, we found early pregnancy (in vitro fertilization) to be characterized by the sequential appearance of hCG, followed by phCG and then cvhCG. Molar ratios of βhCG to βhCG and βhCG to hCG were highest in early gestation. However, there was a reversal of the βhCG to ahCG ratio at 12–13 weeks gestation, and an excess of free ahCG was observed thereafter. Except for values obtained in very early pregnancy, the βhCG to hCG ratio remained remarkably constant at approximately 0.5% throughout gestation. In contrast, choriocarcinoma was distinguished by absolute serum βhCG concentrations 3–100 times greater than the maximum values observed during pregnancy and, more importantly, by exceedingly high βhCG to hCG ratios. For comparison, we studied hCG, ahCG, and βhCG levels in an additional 178 patients with nontrophoblastic tumors. Ectopic production of αhCG and βhCG was rare (3%), and thus far, we have been unable to demonstrate the presence of hCG in such patients. Therefore, hCG and the free subunits appear not to be useful as serological markers for nontrophoblastic tumors. (Endocrinology120: 549–558, 1987) This content is only available as a PDF. Author notes * This work was supported in part by NIH Grants AA-20666, HD-20469, and CA-35711 and a grant from Association pour la Recherche sur le Cancer (Villejuif, France). † Recipient of a research fellowship from Association pour la Recherche sur le Cancer. ‡ Recipient of Research Center Scientist Development Award AA-00048 from the NIH. Copyright © 1987 by The Endocrine Society

Journal

Endocrinology – Oxford University Press

Published: Feb 1, 1987

Keywords: pregnancy; neoplasms; early stage of pregnancy; fertilization in vitro; endocrinology

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