Clinical evaluation of lymphocyte sub-populations and oxygen radical production in sarcoidosis and idiopathic pulmonary fibrosis

Abstract

The purpose of this study was to investigate the relationship between bronchoalveolar lavage (BAL)-derived parameters of interstitial lung disease and clinical and lung function parameters in 34 patients with sarcoidosis and 23 patients with idiopathic pulmonary fibrosis (IPF). BAL findings of healthy individuals served as controls. Cell content and differentiation of BAL fluid were determined. Oxygen radical (O2-) production of BAL cells and of blood polymorphonuclear (PMN) cells was measured. Phenotypes of lung and blood lymphocytes were determined by immunoperoxidase staining. In addition, lung function was assessed, chest X-rays were made and serum ACE was measured. Lymphocyte alveolitis in sarcoidosis was associated with increased alveolar macrophage (AM) O2- production (P < 0.025 vs. sarcoidosis with normal lymphocyte counts). Patients with extrapulmonary sarcoidosis had higher CD4/CD8 ratios in BAL (P < 0.025) and shorter disease duration (P < 0.01) than those with strictly pulmonary sarcoidosis. Disease duration in sarcoidosis correlated inversely with the number of BAL cells (r = -0.38, P < 0.05), the relative and absolute number of lymphocytes in BAL fluid (r = -0.34, P < 0.05 and r = -0.44, P < 0.01, respectively) and the percentage of CD4-positive cells and the CD4/CD8 ratio (r = -0.43, P < 0.05 and r = -0.48, P < 0.025, respectively). Although significant increases in O2- production by BAL cells were observed in both IPF and sarcoidosis, only in sarcoidosis was a higher AM O2- production associated with a significantly lower total lung capacity (r = -0.67, P < 0.005) and pulmonary diffusing capacity TLCO (r = -0.50, P < 0.05). In conclusion, our findings show that lung lymphocyte phenotypes differ among patients with pulmonary and extrapulmonary sarcoidosis and that O2- production is upregulated in active sarcoidosis. In addition, our findings suggest that different relationships between BAL data and lung function in patients with sarcoidosis and IPF may be explained by differences in disease duration. In IPF, disease duration is likely to be underestimated because of its insidious onset. In sarcoidosis, the presence of extrapulmonary symptoms, helpful to establish an early diagnosis, is associated with significant BAL lymphocytosis.