Increased in CD8 T lymphocytes in the BAL fluid of patients with sulfur mustard gas-induced pulmonary fibrosis

Abstract

Objective: In an attempt to understand better the potential role of the T cell in the pathogenesis of pulmonary fibrosis (PF) due to sulfur mustard gas inhalation, this study was designed to analyze bronchoalveolar lavage (BAL) lymphocyte subsets and to determine the ratio of CD4 to CD8 lymphocytes in BAL fluid.

Setting: University hospital.

Patients: Twenty-one veterans with mustard gas-induced pulmonary fibrosis and 20 normal veterans as control group.

Intervention: Chest roentgenograms, pulmonary function tests (PFTs), tests for carbon monoxide diffusing capacity of the lung (DLCO), high-resolution CT scans of the chest, BAL via fiberoptic bronchoscopy, analyses of BAL fluids for cellular and Flow-cytometric analysis of the phenotype of bronchoalveolar cells were performed in all cases. A transbronchial lung biopsy was done in all patients following BAL.

Results: Neutrophilic alveolitis was the predominant feature. Neutrophils (P<0.0001) and eosinophils (P=0.0006) were the predominant cell types in the BAL fluid of patients with PF. CD8 lymphocytes expressed as percentage or absolute number were significantly higher in patients with PF than in healthy controls (22.96+/-7.48% vs. 14.16+/-7.73%, respectively; P=0.0006; and 2.28+/-0.84 vs. 1.10+/-0.55 x 10(3) cells/ml, respectively; P<0.0001). The CD4/CD8 ratio was significantly lower in patients with PF than in healthy controls (0.73+/-0.25 vs. 1.58+/-0.67; P<0.0001). Except for the percentage and the absolute number of the BAL fluid neutrophils (r=0.70, P=0.001: r=-0.62, P=0.005; respectively), no correlation was found between DLCO% and the other BAL cells. A significant negative correlation was observed between the percentage of DLCO and both the percentage and the absolute number of CD8 lymphocytes in BAL fluid in patients with PF (r=-0.81, P=0.0003; r=-0.61, P=0.006; respectively). A significant correlation was also seen between the percentage of DLCO and the CD4/CD8 ratio (r=-0.60, P=0.006) in our patients.

Conclusion: CD8 T cells in BAL fluid were significantly elevated in patients with pulmonary fibrosis. Patients with higher grades of pulmonary fibrosis expressed as percentage of DLCO, revealed higher percentages and the absolute number of CD8 T cells and a lower CD4/CD8 ratio.