1. Department of Medicine, University of Washington School of Medicine and the U.S. Public Health Service Hospital, Seattle, Washington.
2. University of Washington School Medicine.
3. University of Washington School of Medicine.
4. University of Washington School of Medicine; supported by Research career program award 1-K6-AI-2425 from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, U.S. Public Health Service.