ROLE OF NASAL INTERLEUKIN-8 IN NEUTROPHIL RECRUITMENT AND ACTIVATION IN CHILDREN WITH VIRUS-INDUCED ASTHMA

Neutrophil infiltration is a major feature in the pathogenesis of the common cold, and respiratory viral infarction is the major cause of as thma exacerbations. The factors regulating the neutrophil influx are u nknown. Interleukin-8 (IL-8) is a potent neutrophil chemoattractant, w hich has been implicated in several inflammatory diseases. In this stu dy, we investigated the presence of IL-8 chemokine in the nasal aspira tes of asthmatic children (n = 12) in whom asthma was precipitated by proven viral infection. There were increased IL-8 levels in nasal aspi rates from children during the virus-induced asthma exacerbations comp ared with samples from the same children when they had been asymptomat ic for 2 wk (medians 863 and < 20 pg/ml, respectively, p < 0.01). Biol ogical relevance was shown in that IL-8 levels correlate with increase d nasal aspirate neutrophil myeloperoxidase levels and there was also a correlation between myeloperoxidase levels and upper respiratory sym ptom severity. Furthermore, we purified IL-8 from these samples, and d emonstrated biological neutrophil chemotactic. activity. These are the first in vivo data to suggest an important role for IL-8 in neutrophi l influx in proven upper respiratory viral infection associated with a sthma exacerbations. We suggest that IL-8 might provide a target for t herapeutic intervention in virus-induced respiratory diseases.