Antigenic reaction between

An electrode in which an antibody or an antigen/hapten is incorporated in the sensing element is termed an immunoelectrode . The potential response of the immuno-electrode is based on an immunochemical reaction between the sensing element of the electrode and antibody or antigen/hapten in the sample solution. One example of such an electrode is the polymer membrane electrode shown in Fig. 7. The selective response of this electrode to specific immunoglobulins is based on the interaction between antibody in solution and an antigen-ionophore complex in the membrane ... 

Correspondingly, two principal immunohistochemistry methods are employed direct and indirect. The direct method is a straightforward one-step process that creates a direct reaction between the antigen and the labeled antibody. The indirect method requires the use of two antibodies a primary unlabeled antibody and a secondary labeled antibody. 

Antibodies. The reaction between an antibody and its antigen does not result in the chemical modification of the antigen compared with the action of an enzyme and provides the basis for producing chromatographic media capable of selecting the complementary molecules. Either the antigen is insolubilized and used to isolate and purify the appropriate antibodies or with the increased availability of monoclonal antibodies, the reverse procedure is used. 

Table 7.2 Immunological methods of analysis. Demonstrable reactions between antibodies and antigens...

Enzyme-linked immunosorbent assay (ELISA) is based on the specific reaction between an antibody and an antigen. One of the reagents in the reaction is labeled with an enzyme that generates a colorimetric product that can be measured with a spectrophotometric device. The color intensity correlates with the concentration of specific antibody and the respective antigen. The reaction can be formatted in various ways in a multiwell plate (microtiter plate) with the common formats being the sandwich assay, the competitive assay, and the direct assay. (See Figure 11.1.)... 

Precision is a quantitative measure of the random variation between repeated measurements from multiple sampling of the same homogenous sample under specified conditions.27 The weakness of the ELISA is its imprecision. The imprecision is related to the nature of the biological reaction — the reaction between antigen and antibody — and its inherent variability. Typically, the precision of an average ELISA is about 20% relative standard deviation, but can be as high as 30% in some circumstances. 

There have been reports of reactions between house dust and cotton dust antibodies (38) and of allergens in cottonseed proteins by Spies et al T39). Also, byssinosis is uncommon in cottonseed crushing mills. Therefore we looked for the presence of antigens in water extracts of house dust, cottonseed hulls, cottonseed kernel proteins and clean hand picked cotton fibers that had not been baled. The results in Figure 5 indicate that house dust does not contain antigens common to those found in cotton dust. 

Figure 6. Antigen-antibody reaction between the antisera specific for laccase m and laccases I and III.

If some of the antibodies in the antibody population of a serum against antigen A also precipitate with another antigen B, the process is called a cross-reaction between A and B. Cross-reactions are caused by antigenic determinants that A and B have in common. 

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