Abstract
The alveolar macrophage plays a number of important roles in the pathogenesis of silicosis and coal workers' pneumoconiosis (CWP). These roles include phagocytosis of dust particles, release of fibrogenic cytokines, and recruitment and activation of inflammatory cells. Three cytokines, fibronectin, tumor necrosis factor alpha (TNF-α), and interleukin-1β (IL-1β) were measured in the bronchoalveolar lavage fluid (BALF) of controls and asymptomatic coal miners. In addition the alveolar macrophages (AM) from these subjects were analyzed using transmission electron microscopy with X-ray diffraction backscatter in order to determine the number and types of intracellular particles present in these macrophages. Alveolar macrophages from miners contained significantly more particles and silica than controls. Coal miners also exhibited lower levels of TNF-α in lavage fluid. Fibronectin and IL-1β measured in the lavage fluid was not significantly different than controls. This lower TNF-α and lack of elevation of fibronectin and IL-1β in asymptomatic coal miners contrasts with reports of elevated TNF-α in miners with CWP. This disparity may be relevant to the lack of disease in the presence of low-level exposure.