An antibody (see ANTIBODIES) that combines with an ANTIGEN and forms the immune complex as a precipitate. The reaction is used in some diagnostic serological tests to identify antigens in the serum.
n. any antibody that combines with its antigen to form a complex that comes out of solution and is seen as a precipitate. The antibody-antigen reaction is specific; the precipitin reaction is therefore a useful means of confirming the identity of an unknown antigen or establishing that a serum contains antibodies to a known disease. This test may be performed in watery solution or in a semisolid medium such as agar gel. See also agglutination.
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