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

Background: Natural infections bear the risk of triggering MS bouts, wherea s epidemiologic studies have not delineated an increased risk for disease a ctivity after influenza virus vaccination. Objective: To examine influenza A virus-specific and myelin protein-reactive T-cell frequencies by interfer on gamma (IFN gamma)-enzyme-linked immunospot and the response of these cel ls by IFN gamma -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 i nfluenza-specific T cells. Mean antibody responses against influenza A viru s were increased in both populations after 2 weeks (p < 0.01). Despite thes e virus-specific reactions, no increase in T-cell frequencies responsive to human myelin basic protein (MBP) or recombinant human myelin oligodendrocy te protein (MOG) was observed after immunization, arguing against a general immune stimulation by influenza vaccination. In contrast, MBP-specific T-c ell responses became detectable in several individuals after febrile infect ion. Conclusion: These data support the clinical observations that influenz a vaccination is effective and safe in patients with MS with respect to cel lular immunoreactivity against two main CNS myelin proteins.