Association between sputum cytology and lung function in patients with asthma and COPD

Background: Leukocytes present in the airways play very crucial role in the manifestation of obstructive airway disease (OADs). Although some studies have evaluated associations between spirometric variables and sputum leukocyte profile in OADs, association between sputum leukocytes, lung volumes and airway conductance has not been studied extensively. Methods: Among 20 healthy (mean age 63.1±6.7 years), 19 asthmatics (56.4±13.5 years) and 29 patients with chronic obstructive pulmonary diseases (66.3±6.6 years), we measured lung volumes and capacities using spirometry and body plethysmography and quantified leukocytes from induced sputum. We compared the differences lung function variables and sputum cell counts using one-way analysis of variance (ANOVA) and also performed Pearson9s correlation to test the association between sputum leukocyte profile and lung function variables. Results: Specific airway conductance (sGaw) was found significantly reduced (p -1 ] and COPD patients [0.47±0.06 kPa.Sec -1 ] than that of the healthy individuals [1.82±0.26 kPa.Sec -1 ]. sGaw had positive association with sputum macrophages (%) [r=0.55, p=0.002] but significant inverse association with neutrophil (%) [r= -0.44, p=0.02] and neutrophil-macrophage ratio [r= -0.38, p=0.04] in COPD. Functional residual capacity (FRC) also had strong associations with macrophages (%) (r= -0.64, p Conclusion: Poor airway conductance is an important pathophysiological condition in COPD and, which is manifested by increased infiltration of neutrophils in the airways.