Allergy and airway hyperresponsiveness

Allergen-induced airway hyperresponsiveness is a major cause of morbidity in asthmatic patients, and has been suggested to be the cause of perennial asthma in some patients. Allergen-induced airway hyperresponsiveness probably occurs as a consequence of an inflammatory response in the airways initiated by the inhalation of allergen. The relative importance of specific inflammatory cells and mediators in causing airway hyperresponsiveness is not yet known, although eosinophils and neutrophils have been implicated in some animal preparations, and the mediators thromboxane, leukotrienes and PAF may have a role. Drugs which effectively prevent the development of allergen-induced airway hyperrresponsiveness, such as sodium cromoglycate and glucocorticoids, do so by mechanisms not understood. Other drugs with a reasonably specific mechanism of action, such as indomethacin, are useful tools used to investigate the pathogenesis of allergen-induced responses, without having a role in the therapy of asthma.