The high lipid content of respiratory mucins in cystic fibrosis is related to infection.

Seven human bronchial mucins secreted by patients suffering from chronic bronchitis or from cystic fibrosis were prepared by exclusion from a Sepharose CL-2B column in 6 M guanidinium chloride. Their behaviour in CsBr density gradient centrifugation was compared. The mucin fractions were associated with peptides and lipids, the abundance of which decreases with the buoyant density. The lipid content of the mucin fractions appears to be related to the infectious character of the bronchial secretion and seems to be independent of cystic fibrosis. The content of fatty acids remaining after delipidation of mucin fractions from patients with chronic bronchitis or with cystic fibrosis also appears to be related more to the purulent character of the sputum than to cystic fibrosis or chronic bronchitis.