The study of the inflammation of the airway in bronchial asthma by cytological and chemical analysis in the fluid phase of samples taken by sputum induction

Abstract

In recent years the study of samples of bronchial biopsies and bronchoalveolar lavage fluid has made it possible to show the existance of significant airway mucosal inflammation, even in cases of mild bronchial asthma. This has led to a renewed interest in the use of sputum to assess airway inflammation non-invasively. Sputum induction has recently been proposed as a non-invasive alternative to bronchoscopy for the collection of airway secretions from asthmatic subjects. Sputum induction yields satisfactory samples of sputum in the great majority of asthmatic subjects, and both differential cell counts and the measurement of molecular markers of inflammation in the sputum fluid phase are feasible. In this paper we review studies where these measurements have been taken from subjects who were asthmatic, affected by other respiratory pathologies or healthy, and we assess their validity. Finally, we consider possible future clinical applications of sputum measurement of airway inflammation in asthma.