Clinical and Experimental Allergy, 1997, Volume 27, pages 769-779 Comparison of inflammatory cell counts in asthma: induced sputum vs bronchoalveolar lavage and bronchial biopsies D. C. GROOTENDORST, J. K. SONT, L. N. A. WILLEMS, J. C. KLUIN-NELEMANS*, J. H. J. M. VAN KRIEKENf, M. VESELIC-CHARVATt atid P. J. STERK Departments of Pulmonology, *Haematology, Laboratory of Haematomorphology and Immunotyping and "^Pathology. Leiden University Medical Centre. The Netherlands Summary Background Induced sputum potentially allows monitoring of airway inflammation in patients with asthma in a non-invasive way. However, the relationship between the cellular content in sputum and airway tissue has not been fully clarified. Objective We compared the cellular compositions of hypertonic saline-induced sputum, bronchoalveolar lavage fluid (BAL) and bronchial biopsies in 18 clinically stable patients with mild to moderate atopic asthma (baseline FEV,: range 61-114%pred, PC20 methacho- line: 0.04-4.7 mg/mL). They were treated with inhaled short-acting bronchodilators on demand, with (n = 8) or without (n = 10) regular inhaled steroids. Methods Each patient underwent sputum induction and fiberoptic bronchoscopy on separate days in random order. Differential cell counts of induced sputum, bronchoalveolar lavage and bronchial wash were determined on May-Grunwald-Giemsa stained cytospins. Flow cytometry was performed on sputum and BAL samples. Immunohistochemical techniques were used to stain inflammatory cells in 6 fxxn cryostat sections of bronchial biopsies. Results Sputum cell differentials were not different between the patients with and without inhaled steroids, and showed a median value of 19.4% squamous cells, with 1.0% eosinophils, 3.3% lymphocytes, 28.7% neutrophils, 49.4% macrophages and 6.9% cylindric epithelial cells (in percentage non-squamous cells). The percentage eosinophils in sputum was significantly correlated with their percentage in bronchial wash {R^ = 0.52, P = 0.03) and in BAL (/?s = 0.55, P = 0.02), whilst there was a trend towards such a correlation between the number of eosinophils/mL sputum and the number of EG2"'" eosinophils/mm^ lamina propria in bronchial biopsies (7?, = 0.44, P = 0.07). In addition, the percentage of CD4"*" lymphocytes correlated between sputum and BAL {R^ — Q.55, f = 0.03). Conclusion We conclude that the eosinophil counts in hypertonic saline-induced sputum from patients with asthma are related to those in bronchial wash and BAL and, to a lesser extent, with the counts in bronchial biopsies. This suggests that induced sputum can be used to monitor the presence and severity of airway inflammation in asthma. Keywords: airways, bronchoscopy, eosinophils, flow cytometry, lymphocytes Clinical and Experimental Allergy, Vol. 27, pp. 769-779. Submitted 28 June 1996; revised 4 November 1996; accepted 14 November 1996. Correspondence: Professor P. J. Sterk, Lung Function Laboratory, C2-P, Introduction Department of Pulmonology, Leiden University Medical Centre, PO Box rr.ii - r -i. 1.1 ri-- 9600, NL-23OORC Leiden, The Netherlands. ^^e charactenstic feature m the pathology of asthma is Supported by a grant from the Commission of the European Communities airway inflammation [1], which has extensively been inves- (ECSC grant 7280-03-056). tigated in bronchial biopsies and bronchoalveolar lavage © 1997 Blackwell Science Ltd 769