1. Department of Otorhinolaryngology-Head and Neck Surgery; UZ Leuven; Leuven Belgium
2. Laboratory of Clinical Immunology; UZ Leuven; Leuven Belgium
3. ENT Clinic Messidor; Brussels Belgium
4. Department of Otorhinolaryngology; Academic Medical Center; Amsterdam The Netherlands
5. Department of Otorhinolaryngology; University of Ghent; Ghent Belgium