EOSINOPHILIA IN THE RESPIRATORY SECRETION S OF CHILDREN WITH CHRONIC RESPIRATORY-DISEASES - PATHOPHYSIOLOGY AND DIAGNOSTIC IMPACT

The eosinophilic granulocytes are characteristic inflammatory cells in the respiratory mucosa of children and teenagers suffering from aller gic rhinitis or allergic bronchial asthma. That is the basis for the c oncept of eosinophilic mucositis or eosinophilic bronchitis for such d iseases in contrast to the neutrophilic mucositis or neutrophilic (pur ulent) bronchitis due to viral or bacterial infections. By means of th eir aggressive metabolites (major basic protein (MBP), eosinophilic ca tionic protein (ECP), eosinophilic protein X (EPX), or eosinophil-deri ved neurotoxin (EDN), eosinophilic peroxidase (EPO)) the eosinophils p lay a central role in the pathophysiology Of the transition from frequ ently relapsing obstructive bronchitis in early childhood due to infec tions to relapsing obstructive bronchitis of later childhood (= bronch ial asthma) due to allergy, in most cases resulting from bronchial hyp erreactivity. A significant secretory eosinophilia (i.e, more than 13% eosinophils in the cytological smears of nose, pharynx or the tracheo -bronchial wall), is an indicator for the existence of bronchial hyper reactivity, as a rule due to respiratory allergy. The intensity of the airway obstruction (nose, bronchus) does not correlate with the perce ntage of eosinophilia. Bronchoalveolar lavage (BAL) is not a suitable method for detecting secretory eosinophilia. Moreover, persistent eosi nophilia of the respiratory secretions are a sensitive indicator for t he continuous existence of inflammatory processes in the mucosa. Usual ly such cases require not only allergen elimination but also additiona l (topical) steroid administration. Bronchial asthma is under control only if the asthmatic symptoms and the lung function test have been no rmalized and the eosinophilia in the respiratory secretion has disappe ared. The traditional counting of the eosinophils and the quantitative measurement of ECP give comparable results, but in many patients they can vary considerably. The counting of eosinophils should be given pr eference for routine cases (lower cost) whereas for large scale resear ch the ECP determination can be more effective.