Early Antiinflammatory Treatment of Asthma

* Evaluate the change in airway hyperresponsiveness and in inflammatory markers in the blood and sputum in the population studied following a 3-month course of fluticasone 250 µg per day followed by a 9-month course of fluticasone 1000 µg per day (before supper) compared to placebo as measured on a regular basis over a two year period. * This study will include: 1. A baseline evaluation period of 2 weeks before starting the 3-month treatment period followed by the 9-month treatment period. 2. Treatment will be double-blinded, randomized, parallel design. 3. A follow-up period of one year. Optional: Bronchoscopies with bronchial biopsy sampling will be performed before and after tratment in a subgroup of subjects to determine what is the influence of this corticosteroid treatment on airway inflammation and remodelling.