1. *Division of Experimental Immunology and Immunopathology, Department of Pathology, and
2. ‡Department of Pathology, Brigham and Women’s Hospital, Boston, MA 02115; and
3. §Center for Blood Research and Department of Pathology, Harvard Medical School, Boston, MA 02115.
4. †Department of Microbiology and Immunology, University of Louisville, Louisville, KY 40292;