Role of eosinophils in asthma

Eosinophils are the most characteristic inflammatory cells in the airway mu cosa in asthma. Eosinophils release highly toxic products and cytokines whi ch may influence the immune system, amplify the inflammatory response and p articipate in damaging and remodeling processes that occur in the airway mu cosa. Eosinophilic inflammation in asthma is related to the blunted percept ion of bronchoconstriction. The magnitude of eosinophil influx and the degr ee of activation of these cells in the airway mucosa are related to the sev erity of asthma and appear to play a key role in some eases of asthma death . The number and activation of eosinophils in the airway mucosa are related to the magnitude of airway hyperresponsiveness to bradykinin but not to an agonist acting directly on smooth muscle such as methacholine. Inhaled cor ticosteroids reduce eosinophil inflammation in asthma whereas beta 2-agonis ts appear to increase the magnitude of eosinophilic inflammation induced hv allergen exposure. The eosinophilic inflammation can he assessed by non-in vasive methods using sputum analysis and, indirectly by measuring the airwa y reactivity to bradykinin.