Induced sputum: opening a new window to the lung

The interest in sputum assessment as a non-invasive technique to retrieve c ells and soluble material from the lung has increased and gained momentum d uring the last decade. As a marker of inflammation in airway diseases, indu ced sputum (IS) is a particularly promising procedure since it provides spe cific information on both the cellular and molecular constituents in inflam mation. From 1950-1970, sputum cells had been examined on stained smears, w ith the procedure having been applied in both research and clinical setting s. After having been recovered by spontaneous coughing, the cells were used to study lung cancer and respiratory infections and, later on, to diagnose Pneumocystis carinii pneumonia in patients infected with human immuno-defi ciency virus (HIV). The method was widely improved upon by the induction of Sputum with aerosol of hypertonic saline and then extended to become part of the assessment of airway inflammation in bronchial asthma and chronic ob structive pulmonary disease (COPD). It was recently shown that IS can be us ed to study interstitial lung diseases (ILD) and, more specifically, pneumo coniosis, sarcoidosis, non-granulomatous ILD and occupational lung diseases . In light of the fact that immunologic and functional bronchopulmonary abn ormalities may be present in up to two-thirds of patients with Crohn's dise ase, we studied the use of IS in this condition as well. This review analyz es the value of IS and its present applications in pulmonary medicine.