Upper airway x 1: allergic rhinitis and asthma: united disease through epithelial cells.

The relationship between allergic rhinitis and asthma is now established, and most of the clinical, epidemiological and biological data recommend integrated management. Epithelial cells represent the first barrier of the upper and lower respiratory tracts and thus are logical targets for a comprehensive integrated therapeutic approach. This review discusses rhinosinusitis as a co-morbid condition, a precipitating or triggering condition, and an epiphenomenon as an integrated part of the disease. A better understanding and a more pragmatic method of diagnosis and management is needed using cost-effective long-term strategies.