Detection of infliximab levels and anti-infliximab antibodies: a comparison of three different assays

Aliment Pharmacol Ther. 2012 Oct;36(8):765-71. doi: 10.1111/apt.12030. Epub 2012 Aug 28.


Background: Formation of antibodies to infliximab (ATI) inversely correlates with functional drug levels and clinical outcome. Comparison of drug levels and anti-drug antibody monitoring is hampered by lack of standardisation.

Aim: To determine the correlation between three different assays for measuring infliximab and ATI.

Methods: Serum samples and spiked controls (total 62) were evaluated in a blinded way in infliximab and ATI assays developed by Sanquin Amsterdam, Netherlands (A), Laboratory for Pharmaceutical Biology, KU Leuven, Belgium (B) and a commercially available kit from Biomedical Diagnostics (BMD), Paris, France (C) performed by the University Medical Center Groningen (UMCG), Netherlands.

Results: All infliximab assays showed a linear quantitative correlation (Pearson r = 0.91 for A vs. B, 0.83 for A vs. C and 0.73 for B vs. C). Assay C detected infliximab in 11 samples (18%) not detected by A and B, including samples containing only ATI. All ATI assays showed a good linear correlation (Pearson r = 0.95 for A vs. B, 0.99 for A vs. C and 0.97 for B vs. C). Assay A detected ATI in five samples with low ATI that were not detected by assays B and C. Assay B did not detect ATI in three patient samples with low ATI according to assays A and C.

Conclusions: There is a good correlation of infliximab and antibodies to infliximab measurements between these assays. Nevertheless, the Biomedical Diagnostics kit detected false positive infliximab levels in 18% of the samples.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Inflammatory Agents, Non-Steroidal / blood*
  • Anti-Inflammatory Agents, Non-Steroidal / immunology
  • Antibodies / blood*
  • Antibodies, Monoclonal / blood*
  • Antibodies, Monoclonal / immunology*
  • Antigen-Antibody Reactions
  • Biomarkers / blood
  • False Positive Reactions
  • Humans
  • Immunoassay / methods*
  • Infliximab
  • Reagent Kits, Diagnostic / standards
  • Statistics as Topic


  • Anti-Inflammatory Agents, Non-Steroidal
  • Antibodies
  • Antibodies, Monoclonal
  • Biomarkers
  • Reagent Kits, Diagnostic
  • Infliximab