1. Department of Cancer Biology, Harvard University School of Public Health, Boston, Massachusetts 02115
2. Wadsworth VA Hospital, Los Angeles, California 90073
3. Department of Medicine, University of Southern California Orthopedic Hospital, Los Angeles 90007
4. Cellular Immunobiology Unit of the Tumor Institute, University ofAlabama, Birmingham 35294
5. Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322
6. Center for Infectious Diseases, Centers for Disease Control, Atlanta, Georgia 30333