1. From William B. Castle Hematology Research Laboratory, Divisions of Hematology-Oncology, Boston City Hospital and Boston University School of Medicine, Boston, Massachusetts.
2. Division of Hematology, Department of Medicine, Cedars Sinai Medical Center, Los Angeles, California.
3. William B. Castle Hematology Research Laboratory, Divisions of Rheumatology, Department of Medicine, Boston City Hospital and Boston University School of Medicine, Boston, Massachusetts.