Radioimmunoassays and 2-site immunoradiometric "sandwich" assays: basic principles.
The "sandwich" or noncompetitive reagent-excess, 2-site immunoradiometric assay (2-site IRMA), ELISA, USERIA, and related techniques, have several advantages compared with the traditional or competitive radioimmunoassays. IRMAs can provide improved sensitivity and specificity. However, IRMAs present some practical problems with nonspecific binding, increased consumption of antibody, biphasic dose response curve, (high dose hook effect), and may require special techniques for dose response curve analysis. We anticipate considerable growth in the popularity and importance of 2-site IRMA.
Rodbard
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Laboratory of Theoretical and Physical Biology, National Institute of Child Health and Human Development, Bethesda, MD 20892.
D011863:Radioimmunoassay / Q000379:methods*