 In a second step, mild asthmatic subjects will undergo conventional bronchial allergen challenge. IS will be obtained at 6h corresponding to the late asthmatic response and 24h following the challenge. The rhinitic subjects and asthmatic subjects will undergo a 4-day low dose allergen bronchial challenge as well as a nasal allergen challenge. Sputum samples will be obtained following days 2 and 4 of the low dose challenge and one week later, and 24h following nasal challenge. 