Clinical characteristics of study subjects
| Control | Mild asthma | Symptomatic asthma | Severe asthma | |
| n | 37 | 46 | 22 | 17 |
| Age (years) | 30.2 (21–42) | 27.8 (19–43) | 27.8 (19–37) | 49.7 (23–66) |
| Sex (% males) | 62 | 67 | 58 | 30 |
| FEV1 (% predicted) | N/A | 89.6 (70–114) | 75.5 (44–112) | 52.3 (19–79) |
Control = healthy non-atopic volunteers; mild asthma = patients on β2 agonist only with few symptoms and FEV1>70% predicted; symptomatic asthma = patients on β2agonist only with symptoms on a daily basis over preceding seven days; severe asthma = patients with moderate to severe asthma defined by symptoms and FEV1 on inhaled or oral corticosteroids; FEV1 = forced expiratory volume in one second
Results are expressed as mean (range).