NONINVASIVE ASSESSMENT OF BRONCHIAL INFLAMMATION IN ASTHMA - NO CORRELATION BETWEEN EOSINOPHILIA OF INDUCED SPUTUM AND BRONCHIAL RESPONSIVENESS TO INHALED HYPERTONIC SALINE

Bronchial inflammation in mild asthma has been investigated using bron choscopical techniques. The safety of bronchoscopy in patients with mo re severe asthma has been questioned. We have used the non-invasive te chnique of hypertonic saline (HS) inhalation to induce sputum samples for cellular analysis whilst simultaneously yielding a measure of bron chial responsiveness. Ten normal subjects and a heterogenous group of 24 asthmatic patients (range % predicted FEV(1) 43.3-111.5) underwent HS challenge. Sputum samples induced were analysed. Total and differen tial cell counts between the two groups were compared. The association between bronchial responsiveness to HS and sputum cell counts was exa mined in the asthma group. Mean maximum fall in FEV(1) for normal subj ects was 4.0(2.1-5.9, 95%Cl)% after saline. Geometric mean PD20HS for asthma patients was 7.7 (range 0.68-40.92) ml. Adequate sputum samples were obtained from 9/10 normals and 23/24 asthmatic patients. Sputum from normal subjects contained a median of 3.8 (2.8-8.1, interquartile range)% eosinophils compared with 17.6 (8.9-34.1)% in sputum from ast hma patients (P < 0.001). Sputum from asthma patients contained fewer of all other cell types compared with normals, with the difference in macrophages reaching significance. There was no correlation between PD 20HS and cell count for any cell type in asthma subjects. Analysis of induced sputum represents a simple, safe, non-invasive and well-tolera ted method of assessment of bronchial inflammation, suitable for use i n patients with a range of asthma severity. There was no relationship between inflammation, as assessed by sputum cell counts and a measure of 'indirect' bronchial responsiveness.