Antigen excess in modern immunoassays: To anticipate on the unexpected

Joannes F. M. Jacobs*, Renate G. van der Molen, Xavier Bossuyt, Jan Damoiseaux

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


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.
Original languageEnglish
Pages (from-to)160-167
JournalAutoimmunity Reviews
Issue number2
Publication statusPublished - Feb 2015


  • Antigen excess
  • Prozone effect
  • Heidelberger-Kendall curve
  • Immunoassay
  • False negative test-result

Cite this