1. Department of Respiratory Medicine and
2. Department of Pathology, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
3. Department of Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom
4. Department of Pulmonology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
5. National Heart & Lung Institute, Imperial College, London, United Kingdom; and
6. Department of Pulmonology, Chelsea & Westminster Hospital, London, United Kingdom