Specificity, antibody, principles

This example assumes that RIA was chosen. The principle behind RIA is the competition between the analyte A and a radioactively tagged control C (e.g., a /-marked ester of the species in question) for the binding site of an antibody specifically induced and harvested for this purpose. The calibration function takes on the shape of a logistic curve that extends over about three orders of magnitude. (Cf. Fig. 4.38a.) The limit of detection is near the B/Bo = 1 point (arrow ) in the upper left corner, where the antibody s binding sites are fully sequestered by C the nearly linear center portion is preferrably used for quantitation. 

Using an antibody specifically recognizing the antigen-antibody complex, more direct noncompetitive hapten immunoassays, which can be regarded as semi two-site immunometric assay, could be established (S3). Figure 14 depicts two typical procedures of noncompetitive assays using anti-metatype antibodies, which are based on principle C in Fig. 4. 

The 5-HT2C receptors are considered to be restricted to the CNS (139), where they are edited in many isoforms (at least 14) that appear to be differentially distributed (e.g., refs. 140-142). In this context, antibodies specifically directed againt these isoforms could, in principle, allow one to determine their respective or common cellular and subcellular localization. However, the two antibodies available to date (73,143) are directed against the C-terminal portion, a region not affected by the editing. 

The indirect aspect therefore refers to the fact that the specific antiserum against the antigen is not labeled with an enzyme, but a second antibody specific for the particular species in which the first antibody was produced is labeled. Such assays offer flexibility and form the bases of other ELISAs. In principle, the optimization of reagents is similar to the direct ELISA. However, three factors have to be considered ... 

More recently cleanup procedures have been developed purposely for mycotoxins. The principle of immunoaffinity, where an antibody specific to a particular mycotoxin is immobilized onto an inert solid support and packed into a column, is most commonly used. Such a column can be used to absorb a mycotoxin from a known volume of a food extract or liquid with very little, if any, preliminary cleanup. Most of the constituents of the extract pass through the column or can be washed off the column with water. Because the mycotoxins are not covalently bound to the column they can be displaced with an organic solvent such as methanol. This produces a... 

The isotopic dilution radioimmunoassay is based on the principle of saturation analysis, which is outlined in Figure 1. A test compound (in this case insulin, represented by X) is quantified by its ability to progressively saturate a suitable reagent (in this case an antibody specific for insulin, represented by Y). In the first step, a known quantity of radioactively labeled tracer insulin (X ) is added to the sample. 

Much of our insight into the nature of antibody specificity has been acquired through experiments in which haptens were tested for their capacity to inhibit the precipitin reaction of antihapten antibody with a protein-hapten conjugate. The method was exploited for many years by K. Landsteiner and his collaborators, who combined ingenuity with enormous energy and established many of the basic principles of antibody specificity. Their work is summarized in a book published by Landsteiner in 1944 (1), near the end of his career. In the early 1940 s... 

Interstrand links for the a>isomer are maximal after 12 h, while the maximum effect for the ra w-isomer is achieved within 6h [124, 127, 133]. This may mean faster repair of tram binding or slower forming cis linkages, perhaps by a slow two-step reaction. The principle adduct on the DNA is the GG intrastrand link but other linkages, such as AG may form with time [111]. The firmly bound Pt, which is not removable by CN" (see Section 4.2.6), is not recognized by antibodies specific for the Pt—GG link [134] and this indicates that slow-forming adducts may occur. What is the importance of these adducts in cytotoxicity Little monoadduct formation has been observed under the assay conditions employed [136], and the correlation of these adducts with cytotoxicity is at present unclear. 

---