Antibodies detection haptens

Monroe, D. (1989). Novel Liposome Immunoassays for Detecting Antigens, Antibodies, and Haptens. J. Liposome Res. 1 339 - 377. 

The low detection limits of immunoassays depend on the typically high affinities of antibodies for haptens and antigens, as well as the detection limits of the labels used. The detection limit is usually defined as the concentration that yields a signal that is equal to the mean of the blank signal plus two or three standard deviations. This establishes the confidence range for the zero response. For this calculation, the bound/free versus concentration plot is used. While detection limits allow comparisons of different immunoassay methods at the lower concentration end, they say nothing about assay reliability for this reason, both detection limits and precision profiles should be compared. 

The immunochromatographic lateral flow strip test is a one-step test that facilitates low-cost, rapid identification of various analytes at the point of care. We have developed lateral flow strip tests for the specific qualitative or semiquantitative detection of antigens, antibodies, and haptens, such as drug residues. Here, we describe in detail the preparation of three examples of the strip tests for detection of (a) the infectious bursal disease virus (b) Tricbinella specific antibodies, and (c) Clenbuterol residues in urine samples. 

Chemiluminescence continues to be a very selective and sensitive detection tool in FIA immunoassays. The main component in the most commonly used heterogeneous systems is an immunoreactor column, consisting of PTFE tubing packed with immobilized antibodies or haptens. The immunoreac-tion and the chemiluminescence reaction takes place within the immunoreactor, and the emitted light is collected directly from the cell. 

The sensitivity of EIAs is mainly influenced by the assay procedures. Improvement of these variables has led to the development of extremely sensitive EIAs for antigens, antibodies, and haptens. For example, in some cases, the antigen detection limit is at the one zeptomol (lx 10 mol) per assay (33zmolml ) level. 

Conventional ion-selective electrodes have been used as detectors for immunoassays. Antibody binding measurements can be made with hapten-selective electrodes such as the trimethylphenylammonium ion electrode Enzyme immunoassays in which the enzyme label catalyzes the production of a product that is detected by an ion-selective or gas-sensing electrode take advantage of the amplification effect of enzyme catalysis in order to reach lower detection limits. Systems for hepatitis B surface antigen and estradiol use horseradish peroxidase as the enzyme label and... 

Bisulfite modification of cytosine residues also can be used to add permanently a sulfone group to the C-6 position. In this scheme, the sulfone functions as a hapten recognizable by specific anti-sulfone antibodies. At high concentrations of bisulfite and in the presence of methyl-hydroxylamine, cytosines are transformed into N4-methoxy-5,6-dihydrocytosine-6-sulphonate derivatives (Herzberg, 1984 Nur et al., 1989). Labeled antibodies can then be used to detect the hybridization of such probes. 

Immunoassays are based on the ability of the immune system to produce a virtually unlimited variety of antibodies each with a high affinity for foreign compounds (immunogens like viruses, bacteria, proteins, and haptens). Analytically, this phenomenon can be exploited by detection of this immunoreaction using labeled antibodies or antigens (i.e., compounds that can be bound by antibodies). The equilibrium between antibody (Ab), antigen (Ag), and immune complex (Ab-Ag) may be expressed as ... 

At the EM level, detection usually involves using a probe (oligonucleotide) in which a hapten has been incorporated. Incorporation of the hapten does not interfere with the hybridization of the complementary sequences. The next step is the binding of a reporter (may be an antibody) to the hapten. The reporter is then subjected to a binding molecule (may be a secondary antibody) that is coupled with an electron-dense material such as colloidal gold for visualization. Nonetheless, the many affinity-detection and immunodetection systems developed for immuno-cytochemistry may now with ingenuity be applied to molecular biology at the EM level. 

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