Type II pulmonary epithelial cells respond to anthracite coal dust PSOC 867 with increased synthesis of extracellular matrix (ECM) components. Alveolar macrophages modulate this response by pathways that may involve soluble mediators, including tumor necrosis factor- (TNF-) or transforming growth factor-1 (TGF-1). The effects of TNF- (10 ng/ml) and/or TGF-1 (2 ng/ml) were thus investigated in dust-exposed primary type II cell cultures. In control day 1 or day 3 cultures, TNF- and/or TGF-1 had little or no effect on the synthesis of type II cellular proteins, independent of whether the cells were exposed to dust. With PSOC 867 exposure, where ECM protein synthesis is elevated, TNF- and TGF-1 further increased both the absolute and relative rates of ECM synthesis on day 3 but had little effect on day 1. Each mediator increased expression of fibronectin mRNA, as well as of ECM fibronectin content, in a manner qualitatively similar to their effects on synthesis. Thus TNF- and TGF-1 modulate both ECM synthesis and fibronectin content in coal dust-exposed type II cell cultures.