1. Walter Reed Army Institute of Research, Washington, D.C., and National Institute of Arthritis, Metabolism, and Digestive Diseases, Bethesda, Md. 20014.
2. Department of Hematology, Walter Reed Army Institute of Research, Washington, D.C.
3. National Institute of Arthritis, Metabolism, and Digestive Diseases, Bethesda, Md. 20014.