title: Specificity of two-site immunometric assays.
abstract: The assessment of specificity in two-site immunometric assays is complex. Conventional approaches based on standard substitution with cross-reactant may yield misleading results. An 'in-house' immunoradiometric assay (IRMA) for human growth hormone (hGH) appeared free from cross-reactivity with human placental lactogen (hPL) in a single point standard substitution experiment performed by the United Kingdom External Quality Assessment Scheme (UK EQAS). However, detailed studies based on the substitution of hGH standards with hPL cross-reactant, the addition of hPL cross-reactant to hGH standards and the recovery of added hGH from endogenous cross-reactant (sera from pregnant subjects) revealed gross cross-reactivity of hPL in the hGH assay. We recommend that the validation of assay specificity should require the demonstration of quantitative recovery of a range of analyte concentrations from human sera that contain varying endogenous concentrations of cross-reactant.
authors.affiliation: Institute of Biochemistry, Royal Infirmary, Glasgow, UK.
authors.forename: B
authors.initials: B
authors.lastname: Perry
authors.forename: R S
authors.initials: RS
authors.lastname: Chapman
authors.forename: M G
authors.initials: MG
authors.lastname: McConway
authors.forename: D
authors.initials: D
authors.lastname: Griffin
authors.forename: G H
authors.initials: GH
authors.lastname: Beastall
mesh_terms: D002138:Calibration; D003429:Cross Reactions; D005260:Female; D013006:Growth Hormone / Q000378:metabolism*; D006801:Humans; D007158:Immunologic Techniques; D010928:Placental Lactogen / Q000378:metabolism; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D013006:Growth Hormone; D010928:Placental Lactogen