Severity of allergy against Aspergillus fumigatus will be examined using radioallergosorbent test and skin Prick-test. Subsequently, in patients with established sensitization (RAST ≥ 0.35 IU/mL) a specific bronchial provocation with Aspergillus will be performed. In addition, exhaled nitric oxide,carbon monoxide, exhaled air temperature and inflammatory cells in sputum is measured. 24 hours after bronchial allergen provocation, exhaled NO, CO, air temperature, and bronchial responsiveness is determined and a second sputum obtained.