MUCOUS AND SEROUS SECRETIONS OF HUMAN BRONCHIAL EPITHELIAL-CELLS IN SECONDARY CULTURE

Human bronchial surface epithelial cells were maintained in secondary culture on a collagen gel substrate in a defined, serum-free medium. T hese conditions have previously been reported to promote mucous cell d ifferentiation. After 3 wk in culture, approximately 40% of the cells were stained by an antibody directed against human respiratory mucin. Analysis of media from cells cultured in the presence of the radioacti ve precursors [H-3]glucosamine and [S-35]sulfate revealed that the cel ls secreted high molecular weight glycoproteins with properties of typ ical respiratory mucins. In addition, hyaluronic acid and proteoglycan s containing chondroitin sulfate and/or heparan sulfate glycosaminogly cans were identified in cell conditioned media. Finally, Western blot analyses showed that the cells secreted lysozyme and mucous proteinase inhibitor, proteins that are generally considered to be markers for s ubmucosal gland serous cells. These results show that human bronchial cells from the surface epithelium in secondary culture secreted a rang e of glycoconjugates and proteins that were typical secretory products of both mucous and serous cells.