Small Airway Inflammation and Dysfunction in Different Asthma Phenotypes

Inclusion Criteria: * symptoms of asthma and objective evidence of variable or reversible airway obstruction according to at least one of the following criteria * significant response to bronchodilator (in subjects 7 years or older: FEV1 (forced expiratory volume in 1st second) or FVC (forced vital capacity) increases at least 12 % and 200 ml; in 4-6 years old subjects R5 decreases at least 40 %) * in at least 12 years old subjects significant diurnal variation (at least 20 % and 60 l/min on at least three days) or significant response to bronchodilator ( at least 15 % and 60 l/min on at least three occasions) in PEF (peak expiratory flow) during a two-week monitoring * significant airway hyperreactivity (PD20 FEV1 of methacholine less than 600 µg in at least 16 years old subjects, FEV1 decreases at least 15 % in exercise test in 7-15 years old, or R5 increases at least 40 % during free-running test in 4-6 years old subjects) Exclusion Criteria: * current smoking * regular anti-inflammatory asthma medication (will be paused for at least 4 weeks before enrollment) * other chronic pulmonary disease * other diseases that in the opinion of the treating physician prevents participation