Specificity of two-site immunometric assays.
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.
Perry
B
B
Institute of Biochemistry, Royal Infirmary, Glasgow, UK.
Chapman
R S
RS
McConway
M G
MG
Griffin
D
D
Beastall
G H
GH
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
D013006:Growth Hormone; D010928:Placental Lactogen