1. Department of Immunology, The Royal London HospitalWhitechapel, London E1 1BBUK
2. Becton Dickinson France, Belgian Branch N.V., Postbus 13Denderstraat 24, B–9320 Erembodegem–AalstBelgium
3. Department of Haematology, University of CambridgeHills Road, Cambridge CB2 2QHUK