title: Analyte and label binding assay read by flow cytometry.
abstract: A new immunometric two-site sandwich assay is introduced, in which a label-scavenging binding partner is added to the sample in addition to the analyte-binding partner. The scavenger binding partner binds excess label antibody, giving a signal proportional to the amount of excess label antibody in the sample solution. A set of two calibration curves is obtained from the two binding partners simultaneously, and a combination of the two signals gives an unambiguous determination of the analyte concentration, even for high analyte concentrations where the hook effect may occur. Two-particle immunofluorometric assays developed for placental alkaline phosphatase and human chorionic gonadotropin on the basis of this principle and yielding signals measured by flow cytometry gave rapid results (2 h) and had working ranges in excess of 5 and 6 orders of magnitude for the respective analytes.
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim.
authors.forename: J O
authors.initials: JO
authors.lastname: Utgaard
authors.forename: J
authors.initials: J
authors.lastname: Frengen
authors.forename: T
authors.initials: T
authors.lastname: Stigbrand
authors.forename: A
authors.initials: A
authors.lastname: Ullen
authors.forename: R
authors.initials: R
authors.lastname: Schmid
authors.forename: T
authors.initials: T
authors.lastname: Lindmo
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis; D000911:Antibodies, Monoclonal; D006063:Chorionic Gonadotropin / Q000032:analysis; D005260:Female; D005434:Flow Cytometry; D015200:Fluoroimmunoassay / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D007700:Kinetics; D008863:Microspheres; D010920:Placenta / Q000201:enzymology; D012680:Sensitivity and Specificity
chemical_list: D000911:Antibodies, Monoclonal; D006063:Chorionic Gonadotropin; D000469:Alkaline Phosphatase