Patients with cystic fibrosis, a genetically inherited disease, suffer from hypersecretion of abnormally thick mucus that obstructs the air passages of the bronchial tubes. This blockage leads to the development of infections, thereby increasing the severity of the disease. Both the visco-elastic properties of mucus and the ability of bacteria to adhere to it are dependent, at least in part, on the carbohydrates moieties of bronchial mucin glycoproteins. We propose to investigate whether the structures of the carbohydrate side chains of bronchial mucins of patients with cystic fibrosis are aberrant when compared to the carbohydrate side chains of mucins obtained by bronchial lavage of health individuals. The carbohydrate structures of the mucins of cystic fibrosis patients will also be compared to those of the mucins of patients with nongenetic chronic obstructive diseases of air passages that are associated with hypersecretion of mucus, namely, chronic bronchitis and bronchiectasis. Knowledge of the structures of the mucin carbohydrates and whether their structures are aberrant in mucoviscidosis may elucidate the molecular basis of cystic fibrosis.