OBJECTIVE: To analyze cytokine levels in BAL fluid of patients with bronchiectasis due to mustard gas inhalation. PATIENTS: 29 victims with mustard gas-induced bronchiectasis and 25 normal veterans as control group. INTERVENTION: PFTs,, high-resolution CT scans of the chest, analyses of BAL fluids for five cytokines (IL-8, IL-1beta, IL-6, TNF-alpha, IL-12) and analyses of BAL fluids for cellular and flow-cytometric analysis of the phenotype of bronchoalveolar cells were performed in all cases. RESULTS: CD4 lymphocytes expressed as percentage or absolute number were significantly higher in patients with bronchiectasis than in controls (32.17 +/- 16.00 vs 23.40 +/- 6.97%, respectively; p = 0.01; and 3.31 +/- 2.03 vs 1.88 +/- 0.83 x 10(3) cells/ml, respectively; p = 0.001). The CD4/CD8 ratio was significantly higher in patients with bronchiectasis than in controls (3.08 +/- 2.05 vs 1.68 +/- 0.78; p = 0.002). There were significant differences in cytokine (IL-8, IL-1beta, IL-6, TNF-alpha, IL-12) levels of BAL fluid between patients with bronchiectasis and healthy controls.A significant correlation was observed between the HRCT scores and both the percentage and the absolute number of CD4 lymphocytes in BAL fluid in patients with bronchiectasis (r = -0.49, p = 0.009; r = -0.50, p = 0.008; respectively). HRCT scores showed a significant correlation with CD4/CD8 ratios (r = 0.54, p = 0.004) too. Of measured BAL cytokines, only IL-8 (r = -0.52, p = 0.005) and TNF-aalpha (r = 0.44, p = 0.01) showed significant correlations with the HRCT scores. CONCLUSION: The increased levels of cytokines CD4 lymphocytes in the BAL fluid suggest the possible causative mechanism in the lung in sulfur mustard gas-induced bronchiectasis by the recruitment of neutrophils into the lung.