Airway diseases such as asthma and chronic obstructive pulmonary disease (COPD) are characterised by airway hyperresponsiveness, epithelial damage, oxidative stress and airway inflammation. Inflammatory cells, including macrophages, neutrophils, eosinophils and lymphocytes, are crucial in the pathogenesis of asthma and COPD. The prevalence of asthma and COPD is increasing, especially in Western countries. Symptomatic treatment is based on reduction of airway obstruction by inhalation of beta(2)-receptor agonists and attenuation of the underlying inflammatory reactions by inhalation of corticosteroids. Because these agents only suppress symptoms, there is a need for medicines that remove the cause of these airway diseases.