Topics in asthma - Part 1. The importance of allergens in the development of asthma and the persistence of symptoms

The importance of allergies and allergens in the development and persistenc e of asthma is suggested by 3 lines of evidence. First, a number of epidemi ologic studies demonstrate that sensitization to indoor allergens and the s pores of the outdoor seasonal fungus Alternaria is a risk factor for the de velopment of asthma in both children and adults. Sensitivity to pollens, on the other hand, rarely constitutes a risk for asthma but does constitute a risk for seasonal allergic rhinitis. Second, several studies, again in bot h children and adults, have demonstrated that, in persons sensitive to indo or allergens, the severity of asthma symptoms will vary with the level of e xposure. Third, the elimination of exposure to house-dust mites has produce d a remarkable reversal of asthma in sensitive children and adults. Not onl y have symptoms and pulmonary function improved, but there has also been ev idence of a reduction in airway inflammation and hyperresponsiveness. Taken together, these studies make a strong argument for the importance of aller gy and allergen exposure as aggravating factors in asthma in both children and adults and reinforce the importance of the identification and treatment of these allergen sensitivities.