Neutralizing antibodies hamper IFNβ bioactivity and treatment effect on MRI in patients with MS

We measured neutralizing antibodies (NABs) and the in vivo biologic response to interferon-β on neopterin and β 2 -microglobulin blood levels. All NAB-negative patients had an in vivo biologic response (full or partial), whereas all high-level positive patients had no response. High-level NAB patients had more MRI activity than NAB-negative patients ( p = 0.031). Patients with a full response had less MRI activity than patients without biologic response ( p = 0.032).