Influenza vaccination in MS: absence of T-cell response against white matter proteins

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.

To examine influenza A virus-specific and myelin protein-reactive T-cell frequencies by interferon gamma (IFNgamma)-enzyme-linked immunospot and the response of these cells by IFNgamma-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.

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.

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.