EFFECT OF SHORT-TERM NO2 EXPOSURE AN INDUCED SPUTUM IN NORMAL, ASTHMATIC AND COPD SUBJECTS

The aim of this study was to assess the effects of short-term exposure to low levels of nitrogen dioxide (NO2) on airway inflammation. We st udied seven normal, eight mild asthmatic and seven chronic obstructive pulmonary disease (COPD) subjects, All subjects were exposed to air o r to 0.3 parts per million (ppm) NO2 for 1 h, with moderate intermitte nt exercise, on different days and in random order. Before and 2 h aft er exposure, symptom score and results of pulmonary function tests (PF Ts) were assessed, All subjects performed nasal lavage and hypertonic saline (HS) inhalation to collect sputum 2 h after both exposures. Ast hmatic subjects had a higher percentage of eosinophils than normal and COPD subjects in HS-induced sputum after air (asthmatics: median 13 ( range 0.4-37) %; normals: 0 (range 0-2) %; COPD 1.8 (range 0.1-19)%), whilst COPD patients showed a higher percentage of neutrophils than th e two others groups. No significant differences in PFT values or perce ntages of inflammatory cells were observed in nasal lavage and in HS-i nduced sputum in normal, asthmatic and COPD subjects after NO2 exposur e compared to air exposure, except for a mild decrease in forced expir atory volume in one second (FEV1) 2 h after NO2 exposure in COPD patie nts. Symptom score showed a mild increase after NO2 exposure both in n ormal subjects and in COPD patients. We conclude that short-term expos ure to 0.3 ppm nitrogen dioxide does not induce an early detectable ac ute inflammation in proximal airways of normal subjects or of patients with asthma or chronic obstructive pulmonary disease.