False elevation of serum CA-125 level caused by human anti-mouse antibodies

Roger L. Bertholf, Laura Johannsen, Guy Benrubi

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Discordant results were observed for serum CA-125 (carbohydrate antigen-125) assays in a patient who was monitored for recurrence of ovarian cancer. Serum CA-125 levels in this patient were normal when measured in one laboratory, but > 5-times the upper limit of normal (35 U/mL) when measured in another laboratory. Both laboratories used dual antibody heterogeneous immunoassays, but from different manufacturers. Cross-linking heterophilic antibodies were suspected as a cause of the discrepancy, but the interference was not alleviated after 10-fold dilution. Assay of the patient's serum for human anti-mouse antibodies was positive, but only slightly above the reference range. Addition of blocking antibodies eliminated the interference, showing that human anti-mouse antibodies were the cause of the discrepant CA-125 results. These findings indicate that relatively low concentrations of human anti-mouse antibodies can cause significant interference in two-site immunoassays.

Original languageEnglish (US)
Pages (from-to)414-418
Number of pages5
JournalAnnals of clinical and laboratory science
Issue number4
StatePublished - Sep 1 2002


  • Carbohydrate antigen-125
  • Immunoassay interference
  • Ovarian cancer

ASJC Scopus subject areas

  • Microbiology
  • Immunology and Allergy
  • Pathology and Forensic Medicine
  • Immunology
  • Molecular Biology
  • Hematology
  • Clinical Biochemistry
  • Medical Laboratory Technology


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