INCREASED EXPRESSION OF EOTAXIN IN BRONCHOALVEOLAR LAVAGE AND AIRWAYSOF ASTHMATICS CONTRIBUTES TO THE CHEMOTAXIS OF EOSINOPHILS TO THE SITE OF INFLAMMATION

Presently, there is considerable evidence for the participation of eos inophils in the pathophysiology of human bronchial asthma, Although in creased numbers of eosinophils are present in the airways and bronchoa lveolar lavage (BAL) fluid of atopic asthmatics, the mechanisms respon sible for their preferential accumulation are still largely unknown, E otaxin is a chemokine that promotes the selective recruitment of eosin ophils, We report that atopic asthmatic patients have high concentrati ons of eotaxin in BAL fluid and an increased expression of eotaxin mRN A and protein in the epithelium and submucosa of their airways when co mpared with normal controls, In the BAL cells from asthmatic patients, eotaxin immunoreactivity colocalized predominantly to macrophages (62 .2%), with a lesser contribution from T cells (16.3%) and eosinophils (8.9%), BAL fluid from asthmatics contained chemotactic activity for e osinophils that was attributable in part to the presence of eotaxin, M oreover, eotaxin was more effective at inducing in vitro eosinophil ch emotaxis when eosinophils were stimulated with IL-5 (a cytokine that e nhances the effector capacity of mature eosinophils), These observatio ns suggest that eotaxin contributes to the pathogenesis of asthma by t he specific recruitment of eosinophils into the airways.