Antibody avidity

Antibody avidity is commonly applied to antigen-antibody interaction, where multiple, weak, noncovalent bonds form between antigen and antibody. Avidity is distinct from affinity, which is a term used to describe the strength of a single bond. As such, avidity is the combined synergistic strength of bond affinities rather than the sum of bonds. 

Radiolabeled antibody is diluted in BM to an appropriate concentration. Preliminary experiments should be done to determine the binding kinetics and antibody avidity. Routinely we use antibodies at the Kd concentration to give approx half Bmax epitope occupation. 

Antibody avidity is a measure of the functional affinity of antibody to bind to antigen. It is also called as functional affinity. ... 

Perciani, C.T., Peixoto, P.S., Dias, W.O., Kubrusly, F.S., and Tanizaki, M.M. (2007) Improved method to calculate the antibody avidity index. Journal of Clinical Laboratory Analysis, 21, 201 206. 

Abraham R, Moller D, Gabel D, et al. (1991). The influence of periodate oxidation on monoclonal antibody avidity and immunoreactivity. J. Immunol. Meth. 144 77-... 

Modulate antibody avidity, specihcity, isotype, or subclass distribution... 

The definition of an association constant for an antibody—antigen reaction can become more complex if the antibody—antigen reaction iavolves a multivalent antigen, as is the case when a polyclonal antisemm is used for detection of an antigen. This type of multivalent binding is termed avidity and is defined by the equation ... 

Definition of the association (or avidity) constant for such multivalent antibody—antigen reactions must consider not only the heterogeneity of the antibodies and the antigen determinant site(s), but also an apparent additive effect of binding two antigen molecules to a single antibody. Such effects lead... 

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. 

Where more than one antibody in an antiserum can combine simultaneously with an antigen, the sum of the binding strength is defined as the avidity of the antiserum. 

Antibody to peptide Size (amino acid residues) Binding capacity (nmol of antigen per ml of serum) Avidity (liters/mol) Relative binding capacity (%)... 

As discussed previously, murine antibodies have limitations. The next phase of development is to make these murine MAbs more like human antibodies, by using genetic engineering techniques. A recent approach is to humanize the antibodies to reduce HAMA and improve the avidity of the MAbs (avidity... 

Humanized Antibodies To further improve the avidity and reduce antigenicity, only the specific antigen-binding region is derived from mouse, while the remainder of the antibody is constructed using human proteins. These are the humanized antibodies and include the breast cancer targeting MAb called Herceptin (see Case Study 4). 

In general, four factors help to determine the sensitivity of the sandwich ELISA. These factors are (1) the number of molecules of the first antibody that are bound to tbe solid phase (2) the avidity of the first antibody for the antigen (3) the avidity of the second antibody for the antigen (4) the specific activity of the second antibody. By diluting or concentrating the antibody solution, the amount of capture antibody that is bound to the solid phase can be adjusted. In contrast, tbe avidity of the antibodies for the antigen can be altered only by substituting other antibodies. The specific activity of the second antibody is determined by the number and type of labeled moieties it contains. 

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