[Expression of granulocyte-macrophage colony-stimulating factor mRNA by inflammatory cells in the sarcoid lung and its clinical significance].

T lymphocytes and alveolar macrophages accumulating in the lower respiratory tract of patients with pulmonary sarcoidosis are known to be activated to produce several cytokines, presumably leading to granuloma formation within the lung. I hypothesized that these cells produce colony-stimulating factors (CSF), which have been shown to affect the proliferation and function of monocyte/macrophage-lineage cells. To test this hypothesis, I tried to detect mRNA encoding CSFs in cells obtained by bronchoalveolar lavage using a reverse transcription-polymerase chain reaction. Macrophage-CSF mRNA was detected in all subjects examined and interleukin 3 mRNA in none. Granulocyte-macrophage CSF (GM-CSF) mRNA was detected in 15 of 20 patients with pulmonary sarcoidosis, whereas it was detected in none of the farmer's lung disease patients and normal controls. The sarcoid patients whose BAL cells expressed GM-CSF mRNA had more active disease than those patients whose BAL cells did not, as judged from clinical and laboratory findings. These results indicate that GM-CSF produced by the inflammatory cells plays a substantial role in the formation or maintenance of the sarcoid lesion.