Leukotriene B4 Contributes to Exhaled Breath Condensate and Sputum Neutrophil Chemotaxis in COPD.

Background Neutrophils have been implicated in the pathogenesis of COPD. Several chemoattractants for neutrophils have been measured in exhaled breath condensate (EBC) and induced-sputum (IS) from patients with COPD. Objectives The aims of this study were to compare EBC and IS supernatant neutrophil chemotactic activity from ex-smoking COPD and healthy ex-smokers, and to assess the contribution of LTB(4) to this activity. Methods 34 COPD were compared to 24 controls. EBC and IS chemotactic activity for neutrophils were assessed by using Boyden microchambers. Chemotactic index (CI) was used to evaluate cell migration. LTB(4) was measured by a specific enzyme immunoassay. Contribution of LTB4 to EBC and sputum neutrophil chemotaxis was assessed by an LTB(4) receptor antagonist (U-75302: Cayman Chemical Company, Ann Arbor, MI, USA). Results EBC and IS from both COPD and healthy subjects displayed significant neutrophil chemotactic activity but this activity was raised in COPD compared to healthy subjects. Chemotactic activity contained in sputum, however, failed to correlate with that in EBC. In COPD there was a significant correlation between EBC neutrophil chemotactic activity and sputum neutrophil counts. LTB(4) levels were raised in EBC, but not in sputum, from COPD as compared to healthy subjects. LTB(4) receptor antagonist (2.5 10(-4) M) reduced by 44.6% and by 44.4% chemotactic activity contained in EBC and sputum respectively. Conclusions EBC and IS from COPD patients have a raised neutrophil chemotactic activity to which LTB4 contributes.