1. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
2. Department of Microbiology, Brain Korea 21 Project for Graduate School of Medical Science, Yonsei University College of Medicine, Seoul, Korea.
3. Institute for Immunology and Immunological Disease, Yonsei University College of Medicine, Seoul, Korea.