INTERLEUKIN-8 - AN IMPORTANT CHEMOATTRACTANT IN SPUTUM OF PATIENTS WITH CHRONIC INFLAMMATORY AIRWAY DISEASES

Sputum from patients with cystic fibrosis, bronchiectasis, and chronic bronchitis contains neutrophils and neutrophil proteases, which have been implicated in the pathophysiology of mucus hypersecretion in airw ays. We asked whether interleukin-8 (IL-8), a potent neutrophil chemoa ttractant, might be involved in recruiting neutrophils into airways of patients with cystic fibrosis, bronchiectasis, and chronic bronchitis . We found significant neutrophil chemotactic activity in sputum obtai ned from these patients. The IL-8 concentrations that we measured in s putum of patients with cystic fibrosis (7.1 +/- 1.0 x 10(-9) M, mean /- SE), bronchiectasis (9.6 +/- 2.9 x 10(-9) M), and chronic bronchiti s (2.8 +/- 1.0 x 10(-9) M) have been reported to cause significant che motaxis in vitro and in airways in vivo, whereas concentrations measur ed in induced sputum from healthy subjects (1.1 +/- 0.3 x 10(-10) M) d o not. A monoclonal antibody to IL-8 significantly inhibited the chemo tactic activity in patients' sputum by 7598%, but not in induced sputu m from healthy subjects (9%). We conclude that IL-8 is an important ch emotactic factor in sputum of patients with cystic fibrosis, bronchiec tasis, and chronic bronchitis, and we suggest that IL-8 accounts, at l east in part, for neutrophil recruitment into airways of patients with these diseases.