The purpose of this study is to determine whether asthmatics have different adenosine receptor expression profiles than healthy controls. We hypothesize that asthmatics will have increased adenosine receptor expression versus control subjects.

We also want to study the effects of allergen inhalation on adenosine receptor expression in asthmatics. We believe that adenosine receptor expression will be upregulated after allergen inhalation.

Both hypotheses are being tested in sputum and peripheral blood.

Asthmatic Subjects - Inclusion Criteria:

• Clinical diagnosis of asthma
• Steroid naive or subjects not using their inhaled steroids for the last 4 weeks, short-acting beta-agonist for rescue medication
• FEV1 > 70% of predicted
• Positive skin prick test for house dust mite, cat or grass pollen
• PC20 methacholine or histamine < 8 mg/ml

Asthmatic Subjects - Exclusion Criteria:

• Use of systemic steroids in the previous 6 weeks
• Asthma exacerbations in the previous 6 weeks
• Current or ex-smokers with ≥ 10 pack-years (≥ 2 pipe pack-years), ex smokers who stopped less than 1 year ago

Healthy Subjects - Inclusion Criteria:

• No airway complaints
• FEV1 > 90% of predicted
• Negative skin prick test
• PC20 methacholine or histamine > 8 mg/ml

Healthy Subjects - Exclusion Criteria:

• Use of steroids in the previous 6 weeks
• Current or ex-smokers with ≥ 10 pack-years (≥ 2 pipe pack-years), ex smokers who stopped less than 1 year ago