Eosinophilic inflammation in cough variant asthma.

Eosinophils are considered to play a central pathogenetic role in asthma. We previously reported that sputum eosinophilia was observed in patients with cough variant asthma (CVA), as well as in "classic" asthma with wheezing. This study was undertaken to further investigate the involvement of eosinophils in CVA. The serum eosinophil cationic protein (ECP) level, the percentage of eosinophils in bronchoalveolar lavage (BAL) fluid, and the number of eosinophils in bronchial biopsy specimen were examined in 14 patients with CVA, 21 with classic asthma, and in seven healthy controls. For the two asthmatic groups, the clinical severity was classified with scores of 1-3. Pulmonary function and bronchial responsiveness were not significantly different between the patients with classic asthma and those with CVA. BAL, tissue eosinophil and serum ECP were all significantly increased in both classic asthma and CVA when compared with the controls but were not different between classic asthma and CVA. In both groups of asthmatics, the clinical severity significantly correlated with serum ECP and tissue eosinophils. In conclusion, eosinophilic inflammation is involved in cough variant asthma as well as in classic asthma. Anti-inflammatory treatment may be essential in patients with CVA, as in those with classic asthma.