Airway remodeling is a key feature of persistent asthma. Part of the remodeling process involves the laying down of extracellular matrix (ECM) proteins within the airways. In this study we compared the production of ECM proteins by human airway smooth-muscle (ASM) cells in culture after exposure to 10% serum from an asthmatic individual or 10% serum from a nonasthmatic individual with or without beclomethasone (0.01 to 100 nM). Enzyme-linked immunosorbent assays were done with antibodies to human fibronectin; perlecan; elastin; the laminin beta(1), gamma(1), beta(2), alpha(1) chains; thrombospondin; chondroitin sulfate; collagen types I, III, IV, and V; versican; and decorin. Serum from the asthmatic individual, when compared with that from the nonasthmatic individual, caused a significant increase in the production of fibronectin, perlecan, laminin gamma(1), and chondroitin sulfate. Beclomethasone caused a significant reduction in the number of cells exposed to serum from either the asthmatic or nonasthmatic individual, but did not reverse the increase in ECM protein induced by the former. These results suggest an interaction between the ASM and the allergic process that may alter components of the airway wall in asthma, and that corticosteroids may not prevent the fibrosis induced by resident cells within the airways.