DREW PROVAN MD, FRCP, FRCPATH, Emeritus Reader in Autoimmune Hematology, Centre for Immunology, Blizard Institute, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, London, UK. HILLARD M. LAZARUS, MD, FACP, Professor of Hematology-Oncology, Full Professor of Medicine, The Department of Medicine, Division of Hematology-Oncology, Case Western Reserve University, Cleveland, Ohio 44106.