1. From the Division of Rheumatology and Immunology, Department of Medicine, and the Division of Allergy and Immunology, Department of Pediatrics, Duke University Medical Center, Durham, N.C.; the Division of Allergy and Immunology, Department of Pediatrics, University of Nebraska Medical Center, Omaha, Neb.; and Enzon, Inc., South Plainfield, N.J. Address reprint requests to Dr. Hershfield at the Department of Medicine, Box 3049, Duke University Medical Center, Durham, NC 27710.