No interferon-beta antibodies in natalizumab-treated multiple sclerosis patients with progressive multifocal leukoencephalopathy.

BACKGROUND

Interferon beta therapy (IFN-β) can induce production of antibodies (NAbs) that may neutralize both therapeutic IFN-β and endogenous IFN-β, potentially impairing antiviral immunity.

OBJECTIVES

To investigate whether NAbs against IFN-β occur in multiple sclerosis patients that developed natalizumab-associated progressive multifocal leukoencephalopathy (NTZ-PML).

METHODS

Seven NTZ-PML patients were matched with natalizumab-treated patients with prior IFN-β exposure. All were tested for NAbs against IFN-β in serum.

RESULTS

NAbs against IFN-β were absent in all NTZ-PML cases, but present in three matched patients.

CONCLUSIONS

These findings do not suggest a contributing role for IFN-β NAbs in natalizumab-associated PML.