1. Department of Allergy, University Hospital, Reykjavik, Iceland;
2. Department of Respiratory Medicine, University Hospital, Reykjavik, Iceland;
3. Centre for Rheumatology Research, University Hospital, Reykjavik, Iceland;
4. Department of Clinical Physiology, Akademiska Sjukhuset, Uppsala University Hospital, Uppsala, Sweden;
5. Department of Medical Sciences, Akademiska Sjukhuset, Uppsala University Hospital, Uppsala, Sweden;
6. Faculty of Medicine, University of Iceland, Reykjavik, Iceland