1. From the Departments of Pathology (Drs Guzman and Chejfec) and Medicine (Drs Layden and Cotler), University of Illinois, Chicago; the Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Mo (Dr Brunt); and the Department of Pathology, New York University Medical Center, New York (Dr Petrovic). Dr Petrovic is now with the Department of Pathology, Keck School