High concentrations of soluble Fas ligand in bronchoalveolar lavage fluid of patients with pulmonary sarcoidosis.

BACKGROUND AND OBJECTIVES

Sarcoidosis is a systematic granulomatous disorder of unknown origin characterized by accumulation of T lymphocytes and macrophages in multiple organs. We postulated that apoptosis through the Fas/Fas ligand (L) system may be associated with regulation of immune reactions characterized by the formation of noncaseous necrotizing granulomas. Soluble (s) FasL is not equivalent to membrane-associated FasL since conversion of membrane-bound FasL to the soluble form is associated with downregulation of cytotoxicity. To examine the involvement of sFasL in lung inflammation, we compared the levels of sFasL in bronchoalveolar lavage (BAL) fluid and serum of patients with pulmonary sarcoidosis to those of healthy subjects.

METHODS

sFasL was measured in BAL fluid and in serum of 15 patients with active pulmonary sarcoidosis by sandwich ELISA.

RESULTS

High concentrations of sFasL were detected in BAL fluid and serum of patients with sarcoidosis but not in normal subjects. There was a significant correlation between the percentage of lymphocytes and sFasL concentrations in BAL fluid (r = 0.585, p < 0.05).

CONCLUSIONS

Our results suggest that sFasL may be upregulated locally in the lung during the inflammatory process of active pulmonary sarcoidosis.