Test for NAbs against TNF inhibitors

Test result

Test results for neutrealising anti-drug antibodies (NAbs) to TNF inhibitors are reported as negative or positive with titer.

Testing for NAbs against TNF inhibitors are performed only when the concentration of TNF inhibitors activity in serum is < 0.65 µg/mL.


The assay for TNF inhibitor NAbs is based on the same in vitro reporter cell line (iLite) which is used to measure the activity (concentration) of the drug (Lallemand 2011). In short, the NAbs tests show if antibodies in patient serum can prevent TNF-inhibitor activity in an in vitro cell model.

Result interpretation

NAbs are defined as antibodies that prevent TNF-inhibitor binding and thus makes the treatment ineffective.

  • A reduced efficacy of treatment with TNF inhibitors depends in many cases on NAbs against the drug. In case of positive results for NAbs and a secondary treatment failure, it is highly recommended to change the drug as it influences the efficacy of the particular TNF inhibitor.
  • When it is uncertain if the NAbs cause treatment failure, the patient should be followed up with regular monitoring, since there is a high risk that NAbs sooner or later will affect the efficacy of the TNF inhibitor.
  • NAbs do not cross-react between the different TNF inhibitors.

The result interpretation is summarised in algorithms that are found here.

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