Induced sputum compared to bronchoalveolar lavage for evaluating patients with sarcoidosis and non-granulomatous interstitial lung disease

Broncholveolar lavage (BAL), an important tool for evaluating interstitial lung diseases (ILDs), has limited utility due to its invasiveness and the d ifficulty of performing it in clinically contraindicated patients. We compa red BAL with the induced sputum (IS) technique to analyse cells and T lymph ocytes in patients with sarcoidosis (SA) and non-granulomatous ILD (NG-ILD) . Pulmonary function tests and BAL were performed by conventional methods. IS induction was done 20 sec after inhalation of 3.5% saline with an ultras onic nebulizer. Giemsa-stained cytopreps were differentially counted. T lym phocyte subsets were analysed by flow activated cell sorter (FACS). Patient s with NG-ILD had impaired total lung capacity (TLC). Transbronchial biopsy demonstrated lung fibrosis in NG-ILD and non-caseating granuloma in SA. Th e differential cell count in both groups demonstrated a significantly lower percentage of neutrophils and a significantly higher percentage of macroph ages in BAL than in IS. The IS samples of patients with SA were significant ly richer in metachromatic cells and eosinophils, but had a lower percentag e of lymphocytes, compared to the BAL samples. The profiles of T cell subse ts showed the same pattern, in both samples, in both groups. A CD4/CD8 rati o of 2.5 or greater had a sensitivity of 100% and a specificity of 81.2%, w ith a positive predictive value of 81.2% to distinguish SA from NG-ILD. IS is an effective non-invasive technique to identify CD4+ inflammation which distinguishes sarcoidosis from other NG-ILDs. (C) 1999 HARCOURT PUBLISHERS LTD.