Influenza vaccination in MS

Abstract

Background: Natural infections bear the risk of triggering MS bouts, whereas epidemiologic studies have not delineated an increased risk for disease activity after influenza virus vaccination.Objective: To examine influenza A virus–specific and myelin protein–reactive T-cell frequencies by interferon gamma (IFNγ)–enzyme-linked immunospot and the response of these cells by IFNγ-reverse transcription (RT) PCR after immunization and any incidental upper respiratory tract infection (URI) in 12 patients with MS (seven with a relapsing-remitting course; five with a secondary progressive course; Kurtzke Expanded Disability Status Scale [EDSS] score from 1.0 to 6.5, without immunosuppressive treatment) and 28 healthy volunteers.Results: A cellular immune response against influenza A virus was mounted in both populations at 2 weeks after vaccination. Patients with MS showed a higher relative increase (p = 0.008) than controls with respect to the number of influenza-specific T cells. Mean antibody responses against influenza A virus were increased in both populations after 2 weeks (p < 0.01). Despite these virus-specific reactions, no increase in T-cell frequencies responsive to human myelin basic protein (MBP) or recombinant human myelin oligodendrocyte protein (MOG) was observed after immunization, arguing against a general immune stimulation by influenza vaccination. In contrast, MBP-specific T-cell responses became detectable in several individuals after febrile infection.Conclusion: These data support the clinical observations that influenza vaccination is effective and safe in patients with MS with respect to cellular immunoreactivity against two main CNS myelin proteins.