Coating with antibodies

Technologies to purify cells from white cell concentrates are in the research stage. Principles used include antibodies covalently bound to a surface, antibody-coated microbeads in a column, magnetic microparticles that have been coated with antibodies, and hoUow fibers that have been coated with antibodies. 

Nanotechnology has led to very efficient versions of liposomes. Tiny hollow spheres only nanometers in diameter hold even tinier capsules of medicine. The spheres are made of silica covered with gold nanoparticles and when they are coated with antibodies they attach to tumor cells. The spheres are sensitive to light of specific wavelengths and when the light is applied, either heat up and destroy the tumor, or burst, releasing the drugs within the capsules directly into the tumor. 

Microorganisms are more readily phagocytosed when coated with antibody (opsonized). This is due to the presence on the white blood cells of receptors for the Fc fragment ofIgM and IgG (discussed in Chapter 14). Avoidance of opsonization will clearly enhance the chances of survival of a particular pathogen. A substance called... 

The substance to be assayed—e.g., the hormone thyroxine in a serum sample—is pipetted into a microtiter plate (1), the walls of which are coated with antibodies that specifically bind the hormone. At the same time, a small amount of thyroxine is added to the incubation to which an enzyme known as the "tracer" (1) has been chemically coupled. The tracer and the hormone being assayed compete for the small number of antibody binding sites available. After binding has taken place (2), all of the unbound molecules are rinsed out. The addition of a substrate solution for the enzyme (a chromogenic solution) then triggers an indicator reaction (3), the products of which can be assessed using photometry (4). 

With high concentrations of virus, particles will form clumps before much coating with antibody has occurred. With lower concentrations of particles they become evenly coated before aggregating (4). For the latter, use the following method dilute the sap with phosphate buffer, pH 6.5, until less than one rod shaped or filamentous particle or less than five spherical virus particles are seen per field of view at a magnification of 20,000 in a conventional preparation in the electron microscope (see Note 17). Then, follow the method as described. 

Artificial bridging adhesion between cells is known. Immunological procedures which involve the agglutination of cells by an antibody (or antigen when the cells are coated with antibody) appear to be bridging reactions. 

In the sample port the sample is introduced into the test module and the reaction takes place. The fibrous matrix is a glass fibre which is coated with antibody. The conjugate well is prefilled with enzyme conjugate. The substrate well is prefilled with a substrate solution that is used as both substrate and wash solution. The wash port serves to dispense the substrate. 

Nonviral vectors are mostly liposomes of one type or another. Liposomal envelopes can transport substances across cell membranes which would otherwise be repelled by the hydrophilicity of the gene construct. Liposomes may be constructed that are either anionic or cationic. Complex liposomes, coated with antibodies that will target specific antigen presenting cells, can also be designed. 

For the detection and the recovery of specific strains belonging to major STEC sero-groups, IMS can be performed nsing magnetic beads coated with antibodies specific for 026,0111,0103 and 0145 serogronps (commercially available Dynal Ltd, Norway). However, strains recovered with this method must be confirmed for the presence of stx gene to be considered as STEC strains. This methods have not been ISO certified like the IMS for E. coli 0157 H7, but have been employed to help recover STEC strains from food samples (Anvray et al. 2007) or animal faeces (Jenkins et al. 2003). 

Immunoassay has been widely applied in clinical diagnostics for many years. Diagnostic tests were mostly done using directly coated tubes, particles or microplates coated with antibodies or antigens via adsorption or chemical bonding. However, the test performance could adversely be influenced by the many parameters. Therefore, the avidin-biotin (AB) systems were introduced into the clinical laboratory to replace directly bound antibodies and antigens as solid phase matrices. 

Lysis of various target cells coated with antibody by Fc receptor-bearing killer cells, including large granular lymphocytes ( - natural killer cells), neutrophils, eosinophils, and mononuclear phagocytes. 

The first Pz immunosensor for microbial pathogens was developed by Muramatsu et al. in 1986 [65]. Their Pz crystals were coated with antibodies against Candida albicans. The antigen was detected from 1 x 10 to 5 X 10 cells mL The sensor proved to be specific with no detectable response observed with the other species tested. 

The main problem with this form of antigen assay (indirect sandwich I-ELISAs) is that the wells are coated with antibodies that capture antigen. Thus, any subsequent addition of antigen in a test sample will be bound to the wells if it is not fully saturated with the initially added coating antigen. The pretitration of the system then requires that there be no free antibodies coating the wells. Hence, the exact conditions for pretitration may differ from that for the anti-... 

Even more popular than dot blots are microtiter plate assays, so-called ELlSAs (enzyme-linked immunosorbent assay), in which antibody or antigen is loaded into the depression of polyvinyl chloride or polystyrene plates (Kemeny 1994). The depressions are then further coated with antibody, antigen, and enzyme-conjugated antibody in a defined sequence. The antigen is detected via an enzymatic color reaction (Table 6.2). Many companies (Nunc, Flow, Costar, Falcon) offer a palette of products such as 8- or 12-channel pipettes, automatic washing devices, ELISA readers, and so on that make life easier for the friends of ELISA. 

The water sample (160 pL) was incubated 5 min with 160 pL of peroxidase-triazine conjugate in a plastic tube coated with antibody. This was followed by a washing step and then a 2-min incubation with hydrogen peroxide and tetramethy1-benzidine. The reaction was stopped by the addition of dilute sulfuric acid. Deionized water was added to the solution to bring the color intensity at 450 nra to a level appropriate for measurement in a spectrophotometer. 

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