title: A time-resolved fluoroimmunoassay for 18-oxocortisol and 18-hydroxycortisol. Development of a monoclonal antibody to 18-oxocortisol.
abstract: Patients with primary aldosteronism and with glucocorticoid-suppressible aldosteronism excrete in the urine excessive amounts of the hybrid steroids 18-hydroxycortisol and 18-oxocortisol. The measurement of these steroids aids in the differential diagnosis of various adrenal disorders. We have produced mouse monoclonal antibodies against 18-oxocortisol and polyclonal antibodies against 18-hydroxycortisol and describe a time-resolved fluoroimmunoassay (TR-FIA) technique for the measurement of these steroids in the urine. We have also compared this assay with an ELISA technique for these compounds. We also describe the preparation of in-house Eu(III)-labeled avidin and an enhancement solution and compared to a commercially available Eu(III)-labeled streptavidin and enhancement solutions. The monoclonal antibodies against 18-oxocortisol are sensitive and have a high level of specificity. The TR-FIA technique using in-house prepared reagents or commercial ones were indistinguishable from each other, but at a significant saving. The TR-FIA technique was more sensitive and had a greater precision than the ELISA technique for both steroids.
authors.affiliation: Department of Internal Medicine, University of Torino, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Morra di Cella
authors.forename: Franco
authors.initials: F
authors.lastname: Veglio
authors.forename: Paolo
authors.initials: P
authors.lastname: Mulatero
authors.forename: Valerie
authors.initials: V
authors.lastname: Christensen
authors.forename: Keli
authors.initials: K
authors.lastname: Aycock
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhu
authors.forename: Elise P
authors.initials: EP
authors.lastname: Gomez-Sanchez
authors.forename: Celso E
authors.initials: CE
authors.lastname: Gomez-Sanchez
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D015415:Biomarkers / Q000652:urine; D005260:Female; D015200:Fluoroimmunoassay / Q000379:methods*; D006801:Humans; D006854:Hydrocortisone / Q000031:analogs & derivatives* / Q000276:immunology* / Q000652:urine*; D006929:Hyperaldosteronism / Q000652:urine; D008297:Male; D051379:Mice
chemical_list: D000911:Antibodies, Monoclonal; D015415:Biomarkers; C038135:18-oxocortisol; C033689:18-hydroxycortisol; D006854:Hydrocortisone