The impact of NAbs on the clinical management of IFN-b-treated patients generates some debate among neurologists. A recent article summarizes:

Patients who continue to have clinical disease activity despite IFN-b therapy should have their serum levels tested for neutralizing antibodies.... There is controversy about whether patients receiving IFN-b therapy who are doing well should be routinely tested for neutralizing antibodies. Advocates argue that ... it is not possible to rule out ongoing brain inflammation based only on the clinical symptoms. Further studies on the use of neutralizing antibody tests in clinical practice are needed.⁶

Guidelines for using NAb assays suggest, "[w]hen patients are doing poorly and two consecutive blood samples at least three months apart have appropriately positive titers, the patient should be considered NAb positive. The possibility of stopping the drug should be discussed with the patient."³

Figure 1: