Illustration of<unk>  adapted from Schiettecatte et al. The<unk>  or the prozone<unk>  is an immunologic phenomenon whereby the<unk> iveness of antibodies to form immune complexes is sometimes 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 with extremely high concentrations, producing a<unk>  shape on a graph of measurements. There are versions of the<unk>  with excess antibodies and versions with excess antigens. 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.
Hook effect
Martha Mitchell effect
Whitten effect
Ceiling effect 
Bouba/kiki effect
Bystander effect 
Eagle effect
Weekend effect