Chronic bronchial inflammation is an important clinical feature in cystic fibrosis. Approximately 10% of patients with cystic fibrosis suffer from Allergic Bronchopulmonary Aspergillosis. In addition airway inflammation in patients with cystic fibrosis (CF) plays a major role in progression of CF lung disease. In patients with mild disease (Vital capacity >75%) airway inflammation is often under diagnosed.