title: Dual-label time-resolved immunofluorometric assay for simultaneous determination of pregnancy-associated plasma protein A and free beta-subunit of human chorionic gonadotrophin.
abstract: Using time-resolved fluorometry, a simple one-step dual-label immunometric assay has been developed, which allows simultaneous determination of pregnancy-associated plasma protein A (PAPP-A) and free beta-subunit of human chorionic gonadotrophin (beta-hCG) in first-trimester maternal serum samples. Two monoclonal antibodies were biotinylated and immobilized onto the surface of streptavidin-coated microtitration plates, and used to capture PAPP-A and beta-hCG. respectively. Europium (Eu) and Samarium (Sm) chelates were conjugated to two additional monoclonal antibodies acting as detection antibodies for PAPP-A and beta-hCG. The assay was performed using a 4-h one-step format. The within-run precision with buffer-based calibrators was below 8% over the working range of PAPP-A (40-10000 mIU/l) and beta-hCG (7.3-525 micrograms/l) and no hook effect was observed. The intra- and inter-assay coefficients of variation were below 7.1% for serum samples. PAPP-A and beta-hCG concentrations measured by the dual assay in 39 first-trimester serum samples correlated excellently with those obtained by DELFIA single-label PAPP-A (r = 0.997) and the beta-hCG part (r = 0.993) of the DELFIA AFP/beta hCG dual-label assay.
authors.affiliation: Department of Biotechnology, University of Turku, Finland.
authors.forename: Q
authors.initials: Q
authors.lastname: Qin
authors.forename: M
authors.initials: M
authors.lastname: Christiansen
authors.forename: T
authors.initials: T
authors.lastname: Lövgren
authors.forename: B
authors.initials: B
authors.lastname: Nørgaard-Pedersen
authors.forename: K
authors.initials: K
authors.lastname: Pettersson
mesh_terms: D000911:Antibodies, Monoclonal; D001710:Biotin; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood* / Q000276:immunology / Q000592:standards; D005069:Evaluation Studies as Topic; D005260:Female; D015200:Fluoroimmunoassay / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D006801:Humans; D007700:Kinetics; D011247:Pregnancy / Q000097:blood*; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis* / Q000276:immunology / Q000592:standards; D012015:Reference Standards; D015203:Reproducibility of Results
chemical_list: D000911:Antibodies, Monoclonal; D018997:Chorionic Gonadotropin, beta Subunit, Human; D001710:Biotin; D011266:Pregnancy-Associated Plasma Protein-A