Nonisotopic immunoassay

In fact, most RIAs and many nonisotopic immunoassays use a competitive binding format (see Fig. 2). In this approach, the analyte in the sample to be measured competes with a known amount of added analyte that has been labeled with an indicator that binds to the immobilized antibody. After reaction, the free analyte—analyte-indicator solution is washed away from the soHd phase. The analyte-indicator on the soHd phase or remaining in the wash solution is then used to quantify the amount of analyte present in the sample as measured against a control assay using only an analyte-indicator. This is done by quantifying the analyte-indicator using the method appropriate for the assay, for example, enzyme activity, fluorescence, radioactivity, etc. 

D. Rodbard, Mathematics and statistics of hgand assays an illustrated guide, in Ligand Assay Analysis of International Developments on Isotopic and Nonisotopic Immunoassay, ed. J. Langan and J.J. Clapp, Masson, New York, pp. 45-99 (1981). 

Oellerich, M., Klupmann, W.R., Beneking, M., Sybrecht, G.W., Staib, A.H., and Schuster, R., Determination of theophylline in serum by nonisotopic immunoassays (EMIT, SLFIA, NIIA) and HPLC-CA comparative study, Fresenius Z. Anal. Chem., 311,355,1982. 

Varenne, A., Vessieres, A., Salmain, M., Brassier, P., and Jaouen, G. (1995) Production of specific antibodies and development of a nonisotopic immunoassay for carbamazepine by the carbonylmetallo-immunoassay (CMIA) method./. Immunol. Meth. 186, 195-204. 

Vessieres, A., Kowalski, K., Zakrzewski, J., Stepien, A., Grabowski, M., and Jaouen, G. (1999) Synthesis of CpFe(CO)-(L) complexes of hydantoin anions (Cp) eta5-C5H5 (L) CO (PPh3), and the use of the 5,5-diphenylhydantoin anion complexes as tracers in the nonisotopic immunoassay CMIA of this antiepileptic drug. Bioconjugate Chem. 10, 379-385. 

Ishikawa, E., Hashida, S., Kohno, T. and Tanaka, K. Methods for enzyme-labeling of antigens, antibodies and their fragments , in Ngo, T. T. (ed.), Nonisotopic Immunoassay. Plenum Press, New York, 1988, p. 37. 

E. Soini and H. Kojola, Time-resolved fluorometer for lanthanide chelates—a new generation of nonisotopic immunoassays, Clin. Chem. 29, 65—68 (1983). 

Nonisotopic Immunoassays. Nonisotopic immunoassays differ from the isotopic assays only in the type of label used, the end-point measurement, and the separation of bound and free fractions (41-43). 

Methods based on chemiluminescent and bioluminescent labels are another area of nonisotopic immunoassays that continue to undergo active research. Most common approaches in this category are the competitive binding chemiluminescence immunoassays and the immunochemiluminometric assays. Chemiluminescence and heterogenous chemiluminescence immunoassays have been the subject of excellent reviews (91, 92). Detection in chemiluminescence immunoassays is based on either the direct monitoring of conjugated labels, such as luminol or acridinium ester, or the enzyme-mediated formation of luminescent products. Preparation of various derivatives of acridinium esters has been reported (93, 94), whereas a variety of enzyme labels including firefly or bacterial luciferase (70), horseradish peroxidase (86, 98), and alkaline phosphatase are commercially available. 

Nonisotopic Immunoassay with Monoclonal or Clonotype Antibody. 91... 

The essential criteria for a useful analytical technique are specificity, sensitivity, accuracy, precision, simplicity, rapidity, economy, wide applicability, and freedom from hazard. It is well known that radioimmunoassay (RIA) was developed in 1959 by Yalow and Berson (Yl). Since then the radioimmunoassay method has been widely used in the field of clinical chemistry. Radioimmunoassay has inherent in it the advantages listed above. However, this method always requires special facilities for use and disposal of radioisotopes and consideration must be given to the fact that the labeled substances have short half-lives. Immunoassay methods are explosively increasing in use and development as an analytic technique in basic science as well as in clinical laboratory medicine (L1-L3, VI). With these points as background, efforts have been made to develop nonisotopic immunoassay methods or alternative immunoassay methods that are based on antigen-antibody reactions but do not involve use of a radioisotope. 

Forerunners of nonisotopic immunoassay had already appeared before radioimmunoassay was developed. For example, nephelometry is based on precipitation, which is known as the classical immune reaction, and the ideas of particle immunoassay and viroimmunoassay seem to have developed from the hemagglutination test. The principles of enzyme and fluorescence immunoassay had already been used as enzyme and fluorescence antibody techniques in histochemical analysis. In 1971, two groups reported use of an enzyme immunoassay (E5, V2). Leute et al. reported spin immunoassay, which has spurred recent development of nonisotopic immunoassays (L5). 

Up to the present time, various techniques of nonisotopic immunoassay have been developed. Substances to be measured by these techniques include hormones (peptide and nonpeptide), biologically active trace substances, carrier proteins, immunoglobulins, viruses, tumor markers, antibodies against microorganisms (viruses, bacteria, and parasites), autoantibodies, etc. Innumerable papers concerning nonisotopic immunoassay have been published, and enzyme (15, Kl, N5, N6, PI, S2, V4, W9) and fluores-... 

Immunoassay is a type of binding or ligand assay that depends on the antigen-antibody reaction. The various nonisotopic immunoassays that have been used can be divided into several groups as shown in Table 1. 

Table 9 lists various congenital disorders and the immunoassay methods recommended for their mass screening. Most of the substances listed in Table 9 have been measured by radioimmunoassay, but a nonisotopic immunoassay such as enzyme immunoassay is now recommended. Sections 7.1 and 7.2 describe examples of mass screening by enzyme immunoassay. 

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