1. Division of Infectious Diseases, Department of Pediatrics, Rainbow Babies and Children's Hospital,1 and
2. Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 021152; and
3. Abgenix, Inc., Fremont, California 945553
4. Department of Pathology, Case Western Reserve University School of Medicine,4 Cleveland, Ohio 44106;