1. Laboratory of Immunology, I. Medical Clinic, University of Mainz, 55131 Mainz, Germany
2. Gastroenterology Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115
3. Harvard School of Public Health and Harvard Medical School, Boston, MA 02115
4. Immunopathology Unit, Massachusetts General Hospital, Boston, MA 02114
5. Institute of Pathology, University of Heidelberg, 49569 Heidelberg, Germany