The body's response to invaders, such as pollen, bacteria, and viruses, is to trigger its natural defense system. The immune system makes antibodies that stick to the foreign substances and inactivate them. Through this process, known as an immune reaction, antibodies are able to protect the body from potentially harmful foreign substances.
Sometimes, certain interferon medications can cause an immune reaction (i.e., trigger the body to produce antibodies). Keep in mind that not all antibodies are the same, even when formed in response to the same medication. The majority of antibodies formed against interferon medications will not affect how the therapy works. These antibodies, known as binding antibodies, cause no outward effects and are a normal function of the immune system.
Some antibodies, however, can interfere with, or neutralize, the effectiveness of the treatment. In this case, the antibodies produced in response to medications are called neutralizing antibodies (NABs). Experts think that some people on interferon medications ultimately do develop NABs over a long period of time.
All material copyright MediResource Inc. 1996 – 2024. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/healthfeature/gethealthfeature/MS-and-Neutralizing-Antibodies
In the laboratory, scientists think that neutralizing antibodies (NABs) stop the activity of interferon medications. In a person with MS, it is more difficult to figure out the impact of NABs, as there aren't any clear-cut ways to measure it. However, doctors think that NABs usually appear after 6 months of receiving interferon treatment. It is difficult to predict who will and will not develop NABs, but scientists think that they almost always occur by 18 months of receiving interferon treatment in patients who will become antibody positive.
Several research studies have specifically tested for NABs in people with MS receiving treatment with interferon medications. Problems linked to NABs were not always seen in shorter studies (two years or less in duration). Longer-term research (two to four years in duration) has suggested that NABs do interfere with treatment effects. The majority of people with MS will not develop significant levels of neutralizing antibodies and continue to benefit from their treatment. Some people remain free of neutralizing antibodies yet respond poorly to treatment with interferon.
Overall, the most important criteria for determining the effectiveness of your interferon treatment is how you're doing and how you feel, as decided by you and your doctor.
All material copyright MediResource Inc. 1996 – 2024. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/healthfeature/gethealthfeature/MS-and-Neutralizing-Antibodies
Interferon medications (e.g., Avonex®, Betaseron®, and Rebif®) or natalizumab (Tysabri®) can trigger neutralizing antibodies (NABs). The scientific term for this is "immunogenicity." But it is believed that these treatments are not equally immunogenic. That is, the chance that NABs will form is different for each medication.
In previous studies, 28-43% of people on Betaseron® developed NABs, compared to 12-25% of people on Rebif®. Betaseron® NABs seemed to disappear over time, but it is unknown whether Rebif® NABs do the same. Less than 7% of people taking Avonex® developed NABs.
There is no guaranteed way to prevent NABs yet. Some experts say that is best to start people on the least immunogenic interferon so that they're less likely to develop NABs in the first place. The route of administration may also be important, as NAB formation may be decreased with intramuscular injection. Another approach to prevent NABs is to give intravenous corticosteroids, although this would not be recommended on a regular basis without a good reason.
Currently, testing for NABs is not done routinely. Doctors may test for NABs if people are not responding to treatment. However, experts are not convinced of what to do after people test positive for NABs. One option is to stop the interferon medication in people with NABs, wait for the antibodies to disappear, and then start another less immunogenic interferon. Switching interferons without waiting may not be advisable, as NABs can cross-react. Another option may be to increase the dose of interferon. However, this may lead to a serious complication known as immune complex disease (where antibody-interferon clusters get trapped in the kidneys, lungs, skin and joints). Finally, stopping interferon treatment altogether may be an alternative.
All material copyright MediResource Inc. 1996 – 2024. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/healthfeature/gethealthfeature/MS-and-Neutralizing-Antibodies
Neutralizing antibodies (NABs) may be a problem if a person does not improve on interferon, or is not experiencing any flu-like symptoms or side effects (indicating that there is less free interferon floating around to do its main job). Research is ongoing in this area, as there are still many unsolved mysteries.
Talk to your doctor. If both you and your doctor feel that you are not responding well to treatment, and if you have been taking interferon for more than one year, your blood can be tested for NABs. Check with your doctor to see if this test can be done at a laboratory in your area. If you are responding well to your treatment, there may not be a need for testing. Talk to your doctor if you are concerned about NABs and how they may affect the effectiveness of your treatment. Your doctor can help you decide if your treatment plan should be changed. Determining the best treatment plan depends on many factors, including NAB production, side effects, and the general effectiveness of your treatment in helping to relieve your symptoms.
If you are tested for blood levels of NABs, keep in mind that antibody levels fluctuate widely over time in the same person. NABs may disappear completely after 10 years of treatment. Results can differ significantly between laboratories, and your doctor or specialist will interpret the results, particularly because definite guidelines do not yet exist to classify high and low levels of NABs.
All material copyright MediResource Inc. 1996 – 2024. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/healthfeature/gethealthfeature/MS-and-Neutralizing-Antibodies
