1. Department of General Internal Medicine and Clinical Laboratory Medicine, Akita University Graduate School of Medicine, Akita, Japan.
2. Airway Disease Section, Department of Otorhinolaryngology, Kansai Medical University, Hirakata, Japan.
3. Allergy Center, Kansai Medical University, Hirakata, Japan.
4. Division of Pulmonary, Critical Care, and Sleep Medicine, University of California, San Diego, La Jolla, CA, USA.