Abstract

Hyaluronic acid, a connective tissue component, in bronchoalveolar lavage fluid (BAL) is correlated with decreased lung volumes in sarcoidosis. To investigate whether hyaluronic acid could be a marker of fibrosis in another interstitial lung disease, silicosis, the level of the substance in BAL fluid from rats exposed to crystalline silica (n = 3), amorphous silica (n = 3), and in one sham injected rat was measured. There was an increase in the total number of alveolar cells recovered in the rats exposed to crystalline silica and also a pronounced increase in the proportions of neutrophils and lymphocytes. In addition, the concentration of hyaluronic acid was high in this group of rats, and electron microscopic investigation of the lungs showed fibrosis. Thus hyaluronate in BAL fluid in rats exposed to crystalline silica seems to be a possible marker of fibrotic changes.