title: Antigen excess in modern immunoassays: to anticipate on the unexpected.
abstract: Immunoassays measuring sera with high analyte concentration may be prone to an artifact that causes underestimation of the analyte concentration. This phenomenon is generally described as antigen excess or the prozone effect. Characteristically, serum with high concentrations of a certain analyte can give a false negative/low result when tested at the recommended dilution, but reacts strongly positive upon further dilution. Increased insight of the antigen excess mechanisms and tools to prevent it has reduced the analytical problems caused by prozone effects in daily laboratory practice. However, misinterpretation of laboratory results caused by antigen excess does still occur, in virtually any type of immunoassay. Awareness by the laboratory specialist of the mechanisms underlying antigen excess in the different immunoassays, strategies to detect it, and adequate communication with clinicians can help to avoid reporting false negative test-results.
authors.affiliation: Department of Laboratory Medicine, Laboratory Medical Immunology, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA Nijmegen, The Netherlands; Department of Tumor Immunology, Radboud University Medical Center, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands. Electronic address: H.Jacobs@Radboudumc.nl.
authors.forename: Joannes F M
authors.initials: JF
authors.lastname: Jacobs
authors.affiliation: Department of Laboratory Medicine, Laboratory Medical Immunology, Radboud University Medical Center, Geert Grooteplein 10, 6525 GA Nijmegen, The Netherlands. Electronic address: Renate.vanderMolen@Radboudumc.nl.
authors.forename: Renate G
authors.initials: RG
authors.lastname: van der Molen
authors.affiliation: Department of Microbiology and Immunology, Experimental Laboratory Immunology, KU Leuven, Herestraat 49, 3000 Leuven, Belgium; Laboratory Medicine, Immunology, University Hospitals Leuven, KU Leuven, Leuven, Belgium. Electronic address: Xavier.Bossuyt@uzleuven.be.
authors.forename: Xavier
authors.initials: X
authors.lastname: Bossuyt
authors.affiliation: Central Diagnostic Laboratory, Maastricht University Medical Centre, P. Debyelaan 25, 6229 HX Maastricht, The Netherlands. Electronic address: jan.damoiseaux@mumc.nl.
authors.forename: Jan
authors.initials: J
authors.lastname: Damoiseaux
mesh_terms: D000906:Antibodies / Q000276:immunology; D003593:Cytoplasm; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D009504:Neutrophils / Q000276:immunology
chemical_list: D000906:Antibodies
keywords: Antigen excess; False negative test-result; Heidelberger–Kendall curve; Immunoassay; Prozone effect