1. Department of Immunology, Erasmus University Rotterdam (EUR), PO Box 1738, 3000 DR Rotterdam, The Netherlands and Division of Immunological and Infectious Diseases, TNO Prevention and Health (TNO-PG), PO Box 2215, 2301 CE Leiden, The Netherlands
2. National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
3. Neurologische Universitätsklinik, Kantonsspital, Petersgraben 4, CH-4031 Basel, Switzerland