Inflammatory markers in childhood asthma.

The importance of airway inflammation in the pathogenesis of asthma is clearly established. Studies in adults as well as in children have led to the concept that asthma is a chronic inflammatory disease. Airway inflammation is found even in mild asthma. Bronchoconstriction and hyper-reactivity appear to be secondary to the release of inflammatory mediators. The changed view of the pathogenesis of asthma and current emphasis on anti-inflammatory treatment have raised a need for markers that reflect the inflammatory status in the airways. This is of special importance in paediatric practice because lung function tests are less easily performed in young children, and it is preferable to keep steroid doses as low as possible. The eosinophil granulocyte has a multitude of proinflammatory functions and plays a key role in the asthmatic inflammation. It secretes toxic proteins and produces cytokines, which have important roles in airway inflammation. Use of eosinophil granula proteins to monitor inflammation is now finding its place. Measurement of eosinophil cationic protein (ECP) seems to be a valuable complement to the recording of lung function. For paediatric use, measurement of urinary eosinophil protein X (EPX) is promising because it does not require blood sampling.