Enzyme immunoassay principles

K Helgert, et al. Enzyme immunoassay—Principle and application. Pharmazie 44 ... 

Apoptosis and necrosis were detected using the Cell Death Detection EL1SA kit, Roche (Version 11.0), a photometric enzyme-immunoassay for the qualitative and quantitative in vitro determination of cytoplasmic histone associated DNA fragments after induced cell death. Assay is based on a quantitative sandwich enzyme immunoassay principle using mouse monoclonal antibodies directed against DNA and histones that allows specific determination of mono- and oligonucleosomes in the cytoplasmatic fraction of the cell. 

Assay principle Radioimmunoassay (RIA) Microparticle enzyme immunoassay (MEIA)... 

T4. Tanaka, K., Kohno, T, Hashida, S., and Ishikawa, E., Novel and sensitive noncompetitive (two-site) enzyme immunoassay for h tens with amino groups. J. Clin. Lab. Anal. 4,208—212(1990). T5. Towbin, H., Motz, J., Oroszlan, R, and Zingel, O., Sandwich immunoassay for the hapten angiotensin II. A novel assay principle based on antibodies against immune complexes. J. Immunol. Methods 181, 167-176 (1995). 

The principle of this generic immunoassay was further exploited to develop a tube enzyme immunoassay test for on-site screening of urine samples (138). 

The enzyme immunoassay (EIA) applies a single antibody to measure small molecules. The assay works on the principle that two antigens, enzyme-labeled and unlabeled analytes, compete for binding to the limited number of binding sites on the primary antibody, which is subsequently bound to the immobilized anti-IgG. The amount of labeled antigen bound is inversely proportional to the amount of unlabeled antigen (e.g., a cytokine) present in the sample (S7). 

Figure 14. Principle of homogeneous enzyme immunoassay (Reproduced with permission from Ref. 17. Copyright 1973 American Association for Clinical Chemistry, Inc.)...

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). 

Fig. 1. Schematic representation of the principle of homogeneous enzyme immunoassay developed by Rubenstein (emit). [Cited and modified from Fig. IV-4, Miyai, K., in Ishikawa et al., eds. (15).]...

The heterogeneous enzyme immunoassays, which include the enzyme-linked immunosorbent assay (ELISA), are based on the same principles as are used in radioimmunoassays (RIA). In short, after incubation of antigen and antibodies, the antigen-antibody complexes formed are separated from free antigen and antibody by one of a number of different techniques, and the activity in one or both of the fractions is determined. 

An extension of enzyme immunoassay is the enzyme affinity assay applicable to studies of nonimmunological interactions. This is already exemplified by the measurement of hormone using its receptor and by our studies on the interaction of fibronectin with collagen. - Assays of these and similar principles might well become a new area of expression for EIA. 

Principle and procedure Quantitative two-site sandwich-type enzyme immunoassay. 

The method is based on the principle of enzyme immunoassay with fluorimet-ric detection and is termed radial partition immunoassay. This test can analyse macromolecules and haptens rapidly and with high sensitivity in a fully mechanised analysis system. The special feature of this test is the use of carrier-bound reagents on a so-called dry tab. 

Figure 4-16 Principle of nonseparation electrochemical enzyme immunoassay (NEEIA) concept, configured in sandwich immunoassay mode to detect a given protein analyte. Enzyme label on reporter antibody generates an electroactive product that is detected at surface of porous gold electrode when substrate for enzyme is added to the back side of membrane.

Enzyme immunoassays that require physical separation of free and bound T4 are generally based on principles analogous to those of conventional RIAs except that enzyme activity rather than radioactivity is measured. Most enzyme immunoassays use labeled T4 as antigen. An assortment of photometric, fluorescent, and luminescent substrates have been used to monitor the enzyme activity of the antibody-bound fraction. 

Since its introduction in medical research in 1971, various types of enzyme immunoassays have been developed (21) The double antibody sandwich ELISA (DAS-ELISA) introduced in plant pathology in 1976 (23) has become the major test system for plant indexing in the Netherlands This technique can be applied to a wide range of plant pathogens Figure 1 shows the principle for the complex antigen situation for detecting bacteria (23) ... 

Based on the principle of enzyme amplification for enzyme immunoassays adopted in the 1980s, Bobrow and associates developed a catalyzed reporter deposition technique (CARD) to achieve amplified signal for solid-phase immunoassay system and membrane immunoassays. Subsequently, this CARD technique was introduced to IHC in 1992. ... 

E Ishikawa, et al. Principle and applications of ultrasensitive enzyme immunoassay (immune-complex transfer enzyme immunoassay) for antibodies in body fluids. J Clin Lab Anal 7 376, 1993. 

Bannister JV, Higgins IJ, Turner APF. Development of amperometric biosensors for enzyme immunoassay. In Blum LJ, Coulet PR, eds. Biosensor Principles and Applications. New York Marcel Dekker Inc., 2001 7. 

Similar to the principles of biochemical signal amplification, cyclic reaction can provide an effective increase of sensitivity both in amperometric enzyme electrodes and enzyme immunoassays. 

Solvent Extraction Principles. Forensic Sciences Drug Screening in Sport Systematic Drug Identification. Gas Chromatography Mass Spectrometry Chiral Separations. Immunoassays, Techniques Enzyme Immunoassays Luminescence Immunoassays. Liquid Chromatography Column Technology. Pharmaceutical Analysis Sample Preparation. 

See also Bloassays Overview. Derivatizatlon of Analytes. Extraction Solvent Extraction Principles. Fluorescence Food Applications. Food and Nutritional Analysis Contaminants. Gas Chromatography Detectors Mass Spectrometry. Immunoassays Production of Antibodies. Immunoassays, Applications Food. Immunoassays, Techniques Enzyme Immunoassays. Liquid Chromatography Instrumentation Liquid Chromatography-Mass Spectrometry Food Applications. Sampling Theory. 

See alsa Chromatography Overview Principles. Electrophoresis Affinity Techniques. Enzymes Immobilized Enzymes. Immunoassays Ovenriew. Liquid Chromatography Overview Principles Reversed Phase Chiral Multidimensional. 

See also Blood and Plasma. Clinical Analysis Glucose. Enzymes Immobilized Enzymes Enzyme-Based Electrodes Enzymes in Physiological Samples Industrial Products and Processes. Ethanol. Flow Injection Analysis Principles Detection Techniques. Food and Nutritional Analysis Alcoholic Beverages. Forensic Sciences Alcohol in Body Fluids. Immunoassays, Techniques Enzyme Immunoassays. Lipids Determination in Biological Fluids. Pesticides. Process Analysis Bioprocess Analysis. 

See also Food and Nutritional Analysis Mycotoxins. Immunoassays, Techniques Enzyme Immunoassays. Liquid Chromatography Food Applications. Mass Spectrometry Food Appiications. Thin-Layer Chromatography Oven/iew Principles. 

EEIA may be realized in different ways. Homogeneous (non-separation) enzyme immunoassay is based on the principle of modulation of activity of the enzyme label when an antigen binds to an antibody. This means that the activity of an enzyme label may be enhanced (activation) or suppressed (inhibition). In the first case, for instance, the attachment of a thyroxine to malate dehydrogenase causes an inhibition of the enzyme. This inhibition is, however, reversed when this conjugate binds... 

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