Tenascin is increased in epithelial lining fluid in fibrotic lung disorders

Tenascin is an extracellular matrix glycoprotein increased immunohistochemically in tumorous and fibrotic lung tissues as demonstrated by immunohistochemistry. We hypothesized that in bronchoalveolar lavage (BAL) fluid also the tenascin concentration would be elevated in patients with various fibrotic lung disorders. The aim of our study was to investigate whether BAL fluid tenascin would be increased compared with serum tenascin in patients with usual interstitial pneumonia (UIP), sarcoidosis, and extrinsic allergic bronchioloalveolitis. For this purpose BAL fluid was collected from five patients with UIP, 12 patients with sarcoidosis, five patients with extrinsic allergic bronchioloalveolitis, and six patients in a control group. BAL fluid and serum tenascin concentrations were detected by the enzyme immunoassay method. The BAL fluid results were expressed as tenascin concentrations in the epithelial lining fluid (ELF), as estimated by the urea method. The ELF tenascin concentration was increased in the patients with fibrotic lung disorders relative to the control group (mean 0.12 microg/ml) and was highest in the UIP group (mean 5.72 microg/ml) and sarcoidosis group (mean 4.76 microg/ml). It is concluded that the tenascin concentration in the ELF is increased in patients with UIP, sarcoidosis, and extrinsic allergic bronchioloalveolitis, suggesting active synthesis of tenascin in the lower respiratory tract in such disorders.