This study is investigating the possible mechanisms of action of an inhaled treatment (Seretide), currently used worldwide in millions of patients with COPD (Chronic Obstructive Pulmonary Disease) and how it improves the symptoms of these patients. Previous research has failed to identify the mechanisms at play other than dilation of the airways. The research community has long thought the mechanism to be immune based or anti inflammatory but despite intensive research this has not yet been identified.

We aim to recruit equal numbers of healthy smokers, mild, moderate and severe COPD patients (12 patients to be recruited from each group). These patients will never have been prescribed the components present in Seretide (Salmeterol and Flixotide or similar compounds).

The patients will have spirometry at the beginning of the study to confirm the presence of COPD. Healthy smokers will defined as ex or current smokers who match the study population but have normal lung function.

Patients with a history of asthma, bronchiectasis, carcinoma of the bronchus, or other significant respiratory disease will be excluded.

The patients will have a total of four study visits, 2 off treatment and 2 while on treatment, over a 56 day study period. At each study visit induced sputum will be performed and blood extracted. The cells fom both of these samples will be analysed for cells type and activation. Sputum and serum will be stored for cytokine analysis at a later date.

The Sputum will be induced using standardised protocols using nebulised saline solution.

Inclusion Criteria:

• >35yrs.
• >10 Pack Years COPD as defined as an FEV1<70% and an FEV1/FVC ratio of <70%

Exclusion Criteria:

• Asthma
• Lung cancer
• Bronchiectasis