ROLE OF SPUTUM DIFFERENTIAL CELL COUNT IN DETECTING AIRWAY INFLAMMATION IN PATIENTS WITH CHRONIC BRONCHIAL-ASTHMA OR COPD

Background - Sputum may provide an alternative source of bronchial cel ls to investigate characteristics of airway inflammation and its funct ional correlates in patients with asthma or chronic obstructive pulmon ary disease (COPD). Methods - Two groups of clinically stable patients were studied: a group of 43 patients with mild of moderate asthma and a group of 18 patients with COPD. Twenty normal subjects formed a con trol group, Sputum production was either spontaneous or induced with i nhaled hypertonic saline for five minute periods fur up to 20 minutes. The concentration of saline was increased at intervals of 10 minutes from 3% to 4%. Plugs from the lower respiratory tract were selected fo r differential counting in cytocentrifugation preparations. Bronchial provocation tests were performed by inhaling progressive concentration s of histamine from a DeVilbiss 646 nebuliser and the concentration of histamine which caused a 20% fall in the forced expiratory volume in one second (FEV(1)) was calculated (PC(20)FEV(1)). Results - Neutrophi ls predominated in the sputum of subjects with COPD while eosinophils predominated in the sputum of those with chronic asthma, However, in 2 8% of asthmatic subjects an increased percentage of neutrophils was fo und. In asthmatic patients the differential count of eosinophils was i nversely related to the FEV(1), FEV(1)/VC, and bronchial hyper-respons iveness, and directly related to clinical scores. Conclusions - The ce llular profile of sputum ill normal subjects and in patients with asth ma and COPD is different. The concentration of eosinophils in the sput um correlates with the severity of asthma.