1. Laboratory of Experimental Pathology, National Institute of Arthritis and Metabolic Diseases, and the Department of Clinical Pathology, Clinical Center, National Institutes of Health, Bethesda, Md.
2. Clinical Pathology Department, Clinical Center, Bethesda, Md.
3. Hematology Service, Clinical Pathology Department, Clinical Center, Bethesda, Md.
4. National Cancer Institute, on leave from Department of Physiology, University of Melbourne, Australia.
5. National Institute of Arthritis and Metabolic Diseases, on leave from Department of Physiology, University of Melbourne, Australia.