The study investigates the effect of acute smoking and time of day on blood eosinophils in chronic smokers. Chronic cigarette smokers without chronic respiratory diseases smoking at least 8 cigarettes per day and never-smoking controls are examined. Blood eosinophil counts and surface molecules are measured at 8 and 12 am in both groups. In smokers, two measurements are performed (at least 4 weeks apart): one measurement with no smoking between 8 and 12 am, and another measurement with smoking of 8 cigarettes between 8 and 12 am.

20 chronic cigarette smokers without chronic respiratory diseases smoking at least 8 cigarettes per day and 20 never-smoking controls are recruited. Blood eosinophil counts and surface molecules are measured at 8 and 12 am in both groups. In smokers, two measurements are performed (at least 4 weeks apart, cross-over design): one measurement with no smoking between 8 and 12 am, and another measurement with smoking of 8 cigarettes between 8 and 12 am. The effects of the time of day (comparing 8 and 12 am) and the effects of acute smoking (comparing the effects of no smoking or acute smoking at 12 am) on blood eosinophil counts and surface molecules (using flow cytometry) are analyzed. Additional parameters examined: lung function, exhaled nitric oxide, total and specific IgE in serum.

Inclusion Criteria:

• Healthy current smokers
• Age between 18-50 years
• Smoking of at least 8 cigarettes/day

Exclusion Criteria:

• Chronic respiratory diseases
• Any treatment with corticosteroids or other immunosuppressants
• Any acute illness