Antibody specificity

As shown in Table 2, free DAS, as expected, is its own best displacing agent, whereas only DAS—HMS showed any appreciable displacing capabiUty. This can be expected because the hemisuccinate linker is also immunogenic and leads to the production of antibodies specific for the linker in the polyclonal antibody population. AH the other toxins had at least lOOx less the avidity for the antibody, illustrating the specificity of the aDAS for DAS. 

ImmunO lSS iy. Chemiluminescence compounds (eg, acridinium esters and sulfonamides, isoluminol), luciferases (eg, firefly, marine bacterial, Benilla and Varela luciferase), photoproteins (eg, aequorin, Benilld), and components of bioluminescence reactions have been tested as replacements for radioactive labels in both competitive and sandwich-type immunoassays. Acridinium ester labels are used extensively in routine clinical immunoassay analysis designed to detect a wide range of hormones, cancer markers, specific antibodies, specific proteins, and therapeutic dmgs. An acridinium ester label produces a flash of light when it reacts with an alkaline solution of hydrogen peroxide. The detection limit for the label is 0.5 amol. 

A two-site immunometric assay of undecapeptide substance P (SP) has been developed. This assay is based on the use of two different antibodies specifically directed against the N- and C-terminal parts of the peptide (95). Affinity-purified polyclonal antibodies raised against the six amino-terminal residues of the molecule were used as capture antibodies. A monoclonal antibody directed against the carboxy terminal part of substance P (SP), covalently coupled to the enzyme acetylcholinesterase, was used as the tracer antibody. The assay is very sensitive, having a detection limit close to 3 pg/mL. The assay is fiiUy specific for SP because cross-reactivity coefficients between 0.01% were observed with other tachykinins, SP derivatives, and SP fragments. The assay can be used to measure the SP content of rat brain extracts. 

Lascombe, M.-B., et al. Three-dimensional structure of Fab R 19.9, a monoclonal murine antibody specific for the p-azobenzenearsonate group. Proc. Natl. Acad. Sci. USA 86 607-611, 1989. 

Antibodies Specific substances within the human body formed in response to invasion by an antigen. 

A B lymphocyte is a specific type of white blood cell (leucocyte) derived from bone marrow stem cells. Each B lymphocyte expresses an immunoglobulin (antibody) specific for a particular antigen. Following antigenic stimulation, a B lymphocyte may differentiate and multiply into plasma cells that secrete large quantities of monoclonal antibody. 

Antibodies are highly specific, binding only to a restricted part of a given antigen known as an epitope. Given the billions of antibody specificities that may be produced by the immune system, an antibody that recognizes an epitope on virtually any molecule may be produced. It is this property that makes antibodies immensely powerful tools for experimental, diagnostic and therapeutic procedures. 

The first mouse monoclonal antibody specific for human CD3 was produced in 1979 and named orthoclone OKT3. Aside from its use in the laboratory, OKT3 became the first anti-CD3 antibody to be utilized in transplantation medicine, but its wider application was hampered by its immunogenic and mitogenic properties (reviewed in [6]). Consequently, humanized and engineered anti-CD3 antibodies were developed to circumvent these limitations (Table 1). Since T cells and the TCR are involved in many immunological diseases, it is not surprising that the application of CD3 antibodies is not restricted to the field of transplantation. For example, CD3 antibodies are tested in clinical studies of diseases such as autoimmune diabetes (type 1 diabetes), immune-mediated inflammatory arthritis and inflammatory bowel disease [7]. 

AType II allergic reaction occurs when antibodies specific for foreign substances recognize the body s own cells after they have firmly bound these foreign substances and initiate the cell s destruction by immune mechanisms. 

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. 

The preparation of antibodies specific for the individual plasma proteins has greatly facilitated their smdy, allowing the precipitation and isolation of pure proteins from the complex mixmre present in tissues or plasma. In addition, the use of isotopes has made possible the determination of their pathways of biosynthesis and of their turnover rates in plasma. 

When an antigen is injected into an animal, the resulting antibodies are polyclonal, being synthesized by a mixture of B cells. Polyclonal antibodies are directed against a number of different sites (epitopes or determinants) on the antigen and thus are not monospecific. However, by means of a method developed by Kohler and Milstein, large amounts of a single monoclonal antibody specific for one epitope can be obtained. 

Scheme 6. A highly sensitive detection method using an antibody specific for IgG (Fc) and gold nanoparticle...

Enzyme-Mediated Substrate Immunolocalization ofPoIygalacturonic Acid Within Barley Epidermal Cell Walls Utilizing Endopolygalacturonase of Cochliobolus sativus and a Monoclonal Antibody Specific for the Enzyme... 

Palinski, W., Yla-Herttuala, S., Rosenfeld, M.E., Butler, S.W., Socher, S.A., Parthasarathy, S., Curtiss, L.K. and Witztum, J.L. (1990). Antisera and monoclonal antibodies specific for epitopes generated during oxidative modification of low density lipoproteins. Arteriosclerosis 10, 325-335. 

EDTA Ethylenediamine tetraacetic acid ako known as etidronic acid EE Eosinophilic eosinophils EEG Electroencephalogram EET Epoxyeicosatrienoic acid EFA Essential fatty acid EFS Electrical field stimulation EGl Monoclonal antibody specific for the cleaved form of eosinophil cationic peptide... 

Outer cell-wall structures Fluore.scent antibodies Specific antibodies must be available 115, 121... 

Another subset of SPE is immunoaffinity extraction, in which an antibody specific to the analyte is incorporated into the SPE sorbent. This technique is very selective to the analyte and would be very effective in separating the marker residue from tissue-related matrix components. Disadvantages of immunoaffinity extraction are the need to develop a specific antibody-based SPE for each analyte. This approach holds promise for the future as the development of antibody-based methods becomes more commonplace. 

Adalimumab is a recombinant human IgGl monoclonal antibody specific for human TNF.27 Adalimumab binds to soluble and bound TNF-a. Patients may experience symptomatic relief in as early as 1 week. Adalimumab can be administered in combination with methotrexate or other DMARDs.2... 

Currently, there are several assays for the measurement of PSA. All of them contain monoclonal or polyclonal antibodies labeled with enzymatic, fluorometric, or radioactive markers. These assays have shown significant variations within the same patient specimens. These variations may result from differences in antibody specificity, reaction kinetics, calibration, or the system s sensitivity. Studies have shown that only free PSA and PSA-ACT show immunological reactivity in these assays. Also, reaction kinetics can influence the molar ratio. Some of these assays with shorter incubation times may specifically bind the free PSA molecule (which is a lower weight form of PSA). In the equimolar assays, changing the incubation... 

Figure 7.1. Protein expression mapping using an antibody array. The antibody array consists of monoclonal antibodies specific for a set of proteins in the organism of interest gridded onto a filter. To determine if a protein is expressed under the conditions being tested, a crude lysate is obtained and the proteins within the lysate are labeled with a fluorescent tag. The lysate is applied to the filter and the proteins are allowed to bind to the relevant antibody. Bound proteins are visualized via the fluorescent tag.

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