1. Department of Medicine, University of Rochester Medical Center, Rochester , NY 14642.
2. Departments of Pediatrics, Medicine, and Pathology, Medical College of Wisconsin, Milwaukee, WI 53233, and the Blood Center of Southeastern Wisconsin, Milwaukee, WI 53233.
3. Hematology Divisions, Brigham and Women's Hospital, and Departments of Medicine and Pediatrics, Harvard Medical Sool, Boston, MA 02115.
4. Hematology Division, Children's Hospital, and Departments of Medicine and Pediatrics, Harvard Medical School, Boston, MA 02115.
5. Department of Microbiology, University of Rochester Medical Center, Rochester, NY 14642.
6. Hematology Divisions, Brigham and Women's Hospital and Children's Hospital, and Departments of Medicine and Pediatrics, Harvard Medical School, Boston, MA 02115.