Recruitment Methods. Volunteer subjects (healthy non-smokers and healthy smokers) will be recruited from within the National Heart and Lung Institute. Volunteers will be recruited via advertising using ethically approved advertisements. Asthmatic and COPD patients will be recruited from the outpatient clinic at The Royal Brompton Hospital. At the screening visit, the diagnosis of asthma or COPD will be confirmed from the clinical case notes. If the patient is a volunteer, they will undergo a full history and examination, spirometry. Each subject will attend on one study visit only. At the first visit a number of investigations will be undertaken including, spirometry with reversibility (400 microg ventolin via metered dose inhaler if initial spirometry shows an obstructive picture to exclude asthmatics), and sputum induction. In addition, 50ml of venous blood will be taken.