Differences in secretory profiles of epithelial cell cultures derived from human tracheal and bronchial mucosa and submucosal glands.

The respiratory tract contains macromolecules produced by various epithelia including tracheal and bronchial mucosa and submucosal glands. The objectives of this study were to elucidate and compare the growth and secretory profiles of epithelial cell cultures derived from the human tracheal (TC) and bronchial mucosa (BC) and submucosal glands (GC). Most experiments were done on third to fourth passage cultures. Secretory glycoconjugates were characterized by a combination of gel filtration and anion-exchange chromatography after enzymic digestion with hyaluronidase of [3H]glucosamine and [35S]sulphate incorporated glycoconjugates secreted into the culture medium. Intracellular mucin-like glycoproteins were characterized by immunohistochemical staining with a human monoclonal respiratory mucin antibody. Results showed that the three cell types exhibited variable growth rates and secretory profiles. Doubling times of GC, BC and TC were 53, 75 and 80 h respectively. Immunocytochemical staining with the mucin antibody demonstrated positive reaction in GC and BC; TC showed no significant reaction. Mucin-like glycoproteins were detected in the spent media of GC and BC whereas TC, under the same conditions, did not produce any detectable amount of the glycoconjugates. Further, the mucin-like materials produced by GC and BC differed in their relative glycosylation and sulphation levels. The production of mucin was independent of substrate and vitamin A as the cultures were propagated on the plastic surfaces and the culture medium lacked vitamin A.