immunodiffusion

immunodiffusion /im·mu·no·dif·fu·sion/ (-dĭ-fu´zhun) any technique involving diffusion of antigen or antibody through a semisolid medium, usually agar or agarose gel, resulting in a precipitin reaction.

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im·mu·no·dif·fu·sion (my-n-d-fyzhn, -my-)

n.

A technique for studying reactions between antigens and antibodies by observing precipitates formed by the combination of specific antigens and antibodies that have diffused in a gel in which they have been separately placed.

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immunodiffusion

[-difyo̅o̅′zhən]

Etymology: L, immunis + diffundere, to spread

a technique for the identification and quantification of any of the immunoglobulins. It is based on the presence of a visible precipitate that results from an antigen-antibody combination under certain circumstances. Gel diffusion is a technique that involves evaluation of the precipitin reaction in a clear gel, seen when an antigen placed in a hole in the agarose diffuses evenly into the medium. An obvious ring forms where the antigen meets the antibody. Electroimmunodiffusion is a gel diffusion to which an electrical field is applied, accelerating the reaction. Double gel diffusion is a technique that permits identification of antibodies in mixed specimens. In an agar plate antigen is placed in one well, antibody in another. Antigen and antibody diffuse out of their wells. In mixed antigen specimens each antigen-antibody combination forms a separate line; observation of the location, shape, and thickness of a line permits identification and quantification of the antibody.

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immunodiffusion (im´ūnōdifū´-zhn),

n a technique for the identification and quantification of an immunoglobulin.

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immunodiffusion

the diffusion of antigen and antibody from separate wells, usually cut in agar, such that precipitation lines form in the agar between the wells.

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radial immunodiffusion (Mancini technique)

antigen diffuses into the agar which contains specific antibody and a ring of precipitate is formed, the diameter of which is directly proportional to the concentration of the antigen and can thereby be used to quantitate the amount of antigen. A reverse radial immunodiffusion test, in which antigen is incorporated in the agar, can be used to quantitate the amount of antibody in a sample.

immunodiffusion tests

include double immunodiffusion (Ouchterloney technique) which is used in the coggins test for equine infectious anemia and single immunodiffusion (Oudin technique), as well as radial immunodiffusion.