1. Canadian Red Cross Society, Hamilton, Ont. L8N 1H8, Canada
2. Department of Pathology, McMaster University, Hamilton, Ont. L8N 3Z5, Canada
3. Department of Medicine, McMaster University, Hamilton, Ont. L8N 3Z5, Canada
4. The Oklahoma Medical Research Foundation, Hematology Research Program, Oklahoma City, OK 73104, U.S.A.
5. New York Department of Health, Albany, NY 12201, U.S.A.