Effect of antihistamines on epithelial cells

Antihistamines have mostly been used in the management of allergic rhinitis , primarily for their symptomatic relief. Recent studies, however, have sug gested that the non-sedating second-generation antihistamines also possess anti-inflammatory activity, and consequently may be useful in the managemen t of inflammation in allergic airways disease. Several in vivo studies have demonstrated that antihistamines decrease inflammatory cell infiltration i n allergic disease, mediator release from mast/basophil cells, and the expr ession of adhesion molecules on epithelial cells. Similarly, in vitro studi es have demonstrated that antihistamines decrease the migration and activat ion of eosinophils and the release of proinflammatory mediators from mast/b asophil cells, induced by immunological and nonimmunological stimuli. More recent evidence suggests that the antihistamines may modulate airway inflam mation by influencing the activity of airway epithelial cells, which due to their spatial arrangement and predominance in the airways, are thought to play a pivotal role in the aetiology of airway disease. We and others have demonstrated that antihistamines attenuate allergen- or chemical-induced ex pression and/or release of mediators which influence the activity of inflam matory cells, such as eosinophils, mast cells, basophils and lymphocytes, k nown to be involved in the pathogenesis of allergic airway diseases. Collec tively, these studies suggest that second-generation H-1-histamine receptor antagonists may have potential use either as safe anti-inflammatory altern atives to corticosteroids, or as rescue medication in combination with cort icosteroids, for the management of severe airway disease.