1. Mucosal Immunology Unit, Laboratory of Parasitic Diseases, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
2. Immunology Graduate Group, University of Pennsylvania, Philadelphia, PA 19104
3. Center for Neurological Diseases, Brigham Women's Hospital, Harvard's Medical School, Cambridge, MA 02139
4. Gastrointestinal Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114