[Nasal allergy and asthma: one or two diseases?].

Epidemiological studies have shown that rhinitis and asthma are associated. At least four out of five asthmatics suffer from rhinitis and one out of four rhinitic subjects develop asthma. Recent progress in cellular and molecular biology confirms that the same inflammatory cells and similar mechanisms participate in the pathophysiology of the two diseases. Histological findings show that although nasal inflammation resembles bronchial inflammation, specific remodelling features that are present in asthma are lacking in rhinitis. This may be due to the different embryologic origin of the two organs. These similarities explain certain clinical interactions and are the basis of the ARIA (Allergic Rhinitis and its Impact on Asthma)--WHO guidelines recommending that symptoms of rhinitis be sought in asthmatic subjects and symptoms of asthma in rhinitic subjects.