Development of a Novel Non-invasive Inflammometry Following Allergen Challenge in Patients With Mild Allergic Asthma

The goal of this exploratory method-development study is to to establish and evaluate novel non-invasive methods to monitor airway inflammation induced by allergen challenge (both by instillation during bronchoscopy and by inhalation) in patients with mild allergic asthma. The investigator wants to further profile and develop the allergen challenge model by investigating the utility of various non-invasive monitoring methods. The hypothesis of the project is that local inflammatory changes in the lung induced by allergen can be captured by gas-enhanced magnetic resonance imaging (MRI) and analysis of exhaled breath. The validation of cellular outcome measures and non-invasive inflammometry can be used in future clinical trials for proof of concept of novel anti-inflammatory medications. Participants will undergo * methacholine challenge * 2 inhaled allergen challenges * 2 MRI with hyperpolarized xenon and gadolinium based contrast agent * 2 bronchoscopies with bronchoalveolar lavage (BAL) * segmental allergen challenge during the first bronchoscopy * spirometry * skin prick test and skin prick dilution tests * measurement of particles in exhaled air * nasal filter * nasal lavage * sputum induction * peak flow meter tests * exhaled NO (nictric oxide) * blood sampling (in total approx. 190 ml)