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August 13, 1982

Postzone v Prozone-Reply

Author Affiliations

New York State Department of Health Albany

JAMA. 1982;248(6):646-647. doi:10.1001/jama.1982.03330060014013

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In Reply.—  In most titrations, the amount of antibody is varied in the presence of a constant amount of antigen (Fig 2, top). The prozone is then the zone of antibody excess, resulting in an absence of antibody-antigen precipitation or agglutination. The postzone is the comparable zone of antigen excess.In some titrations, however (such as the slide latex agglutination test for cryptococcal antigen), antigen is varied in the presence of a constant amount of antibody (Fig 2, bottom). The zone of antibody excess then follows the zone of equivalence, while the zone of antigen excess precedes it. The terms prozone and postzone thus carry the reverse meanings.Perhaps more distinguishing terms are needed for this phenomenon.