Quartz and Coal Mine Dust treated Human Monocyte-Derived Macrophages Release a Proliferation Factor for Human Lung Fibroblasts (WI-38)

Silicosis is a chronic fibrotic lung disease caused by inhalation of quartz containing dusts in coal mine workers, stone masons and quarriers. It is characterized by an increase in collagen content of the lung, leading to parenchyma destruction and impairment of pulmonary functions. In the lung alveolar macrophages are the primary target of the noxious effect of quartz containing dusts. Macrophages form a large number of more than 100 “mediators” or “biofactors” which are involved in inflammation, tissue repair and immunological processes (Nathan, 1987). It is assumed today that mononuclear cells, especially monocytes and macrophages are involved in fibrosis by mediators or cytokines which induce enhanced growth and collagen formation by fibroblasts (Heppleston, 1991). In the present study we report about the kinetics of DNA-synthesis of human lung fibroblasts (Wistar 38) after addition of supernatants from quartz dust DQ 12 or coal mine dusts treated human macrophages. The percentage of DNA synthesizing human lung fibroblasts was determined by an immunochemical staining method after incorporation of the thymidine-analogous 5-bromo-desoxyuridine.