The hook effect refers to the prozone phenomenon, also known as antibody excess, or the postzone phenomenon, also known as antigen excess. It is an immunologic phenomenon whereby the effectiveness of antibodies to form immune complexes can be impaired when concentrations of an antibody or an antigen are very high. The formation of immune complexes stops increasing with greater concentrations and then decreases at extremely high concentrations, producing a hook shape on a graph of measurements. An important practical relevance of the phenomenon is as a type of interference that plagues certain immunoassays and nephelometric assays, resulting in false negatives or inaccurately low results. Other common forms of interference include antibody interference, cross-reactivity and signal interference. The phenomenon is caused by very high concentrations of a particular analyte or antibody and is most prevalent in one-step (sandwich) immunoassays.[2][3]
- ^ Schiettecatte, Johan; Anckaert, Ellen; Smitz, Johan (2012-03-23). "Interferences in Immunoassays". Advances in Immunoassay Technology. InTech. doi:10.5772/35797. ISBN 978-953-51-0440-7.
- ^ Greenberg, G R; Jeejeebhoy, K N (1989-03-01). "Reply". Gut. 30 (3): 422–423. doi:10.1136/gut.30.3.422-a. ISSN 0017-5749. PMC 1378475.
- ^ Jacobs, Joannes F. M.; van der Molen, Renate G.; Bossuyt, Xavier; Damoiseaux, Jan (2015-02-01). "Antigen excess in modern immunoassays: To anticipate on the unexpected". Autoimmunity Reviews. 14 (2): 160–167. doi:10.1016/j.autrev.2014.10.018. ISSN 1568-9972. PMID 25461469.