1. Department of Internal Medicine, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan 614-735, Korea.
2. Institute of Allergy and Clinical Immunology, Seoul National University Medical Research Center, Seoul 110-799, Korea.
3. Department of Internal Medicine, Pusan National University College of Medicine, Busan 626-870, Korea.
4. Department of Internal Medicine, Pusan National University Yangsan Hospital, Yangsan 626-700, Korea.
5. Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-799, Korea.
6. Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam 463-707, Korea.
7. Department of Internal Medicine, Korea University College of Medicine, Seoul 136-705, Korea.
8. Department of Internal Medicine, Eulji General Hospital, Eulji University School of Medicine, Seoul 139-711, Korea.
9. Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Korea.
10. Department of Allergy and Clinical Immunology, Ajou University School of Medicine, Suwon 443-721, Korea.