Antibodies are proteins produced by the immune system as part of the response to foreign objects, such as bacteria and viruses. Sometimes the body's natural defences will develop antibodies against drugs entering the body, reducing (or neutralising) the drug's effectiveness.
It is known that people with multiple sclerosis can develop neutralising antibodies to some disease modifying drugs. Treatment with one of the beta interferon drugs (Avonex, Betaferon, Extavia and Rebif) or Tysabri (natalizumab) can lead to the development of neutralising antibodies. The majority of people will not develop significant levels of neutralising antibodies and in some people they may reduce again over time. It is recommended that people taking one of the beta interferon drugs are tested to monitor for the presence of neutralising antibodies.
Although neutralising antibodies are not associated with any new side effects or long-term safety issues, they can reduce the drug’s effectiveness. If you are taking one of these drugs and notice you' are having more relapses than you used to, it could be that you have developed neutralising antibodies against it. If you notice any changes, contact your MS team. A blood test may be performed if the presence of neutralising antibodies is suspected. Depending on the results, the neurologist may then discuss whether to continue with treatment, or suggest switching to another disease modifying drug.
- European Journal of Clinical Pharmacology 2015 Aug 14. [Epub ahead of print] Summary Development of interferon beta-neutralising antibodies in multiple sclerosis-a systematic review and meta-analysis.
- Neurology 2007;69(14):1391-1403. Summary The incidence and significance of anti-natalizumab antibodies: results from AFFIRM and SENTINEL.
- European Journal of Neurology 2005;12(11):817-827. Summary Guidelines on use of anti-IFN-beta antibody measurements in multiple sclerosis: report of an EFNS taskforce on IFN-beta antibodies in multiple sclerosis.
Last updated: November 2017
Last reviewed: September 2015
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