Th1 cytokine pattern in sarcoidosis is expressed by bronchoalveolar CD4(+)and CD8(+) T cells

The pathogenesis of pulmonary sarcoidosis has been related to an increased production of Th1-like cytokines. However, cytokine expression in sarcoidos is has not been systematically studied at a single-cell level. We therefore investigated the expression of IL-2, IL-4, IL-13, tumour necrosis factor-a lpha (TNF-alpha) and interferon-gamma (IFN-gamma) intracellularly in bronch oalveolar lavage (BAL) and peripheral blood CD3(+) T lymphocytes from patie nts with pulmonary sarcoidosis (radiologic stage II-III, n = 8) and normal controls (n = 9) by flow cytometry. In contrast to IL-4 and IL-13, the perc entage of T lymphocytes expressing intracellular IL-2 (49.3 +/- 21.3% versu s 14.5 +/- 15.6%), IFN-gamma (75.5 +/- 14.9% versus 32.6 +/- 18.7%) and TNF -alpha (68.3 +/- 18.7% versus 36.8 +/- 20.8%) was significantly higher in p atients with sarcoidosis than in normal controls (each P < 0.005). In contr ast to BAL lymphocytes, expression of these cytokines in peripheral blood l ymphocytes did not differ between patients with sarcoidosis and normal cont rols. Close correlations were observed between the percentages of BAL lymph ocytes expressing intracellular IL-2, IFN-gamma and TNF-alpha, but not for IL-4 or IL-13. Analysis of the expression of these cytokines in T lymphocyt e subsets revealed IL-2, IFN-gamma, and TNF-alpha in CD4(+) as well as CD8( +) T lymphocytes, suggesting a contribution of TC1 cells to the production of proinflammatory cytokines in sarcoidosis. We conclude that a Th1-like cy tokine pattern can be observed in CD4(+) as well as in CD8(+) BAL T lymphoc ytes in patients with pulmonary sarcoidosis.