Physicochemical Differences of Mucoproteins in Duodenal Fluid of Patients With Cystic Fibrosis of the Pancreas and Controls

An abnormality of mucous secretions has been postulated repeatedly in order to explain many of the pathologic findings and clinical symptoms of cystic fibrosis of the pancreas. However, little evidence in support of this hypothesis has been forthcoming heretofore. Investigations reported in this paper have shown that the mucoproteins in duodenal fluid obtained from patients with cystic fibrosis of the pancreas have a different physicochemical behavior as compared with a group of controls. In 89 out of 92 normal individuals and patients (children and adults) with a variety of disease the mucoproteins of duodenal contents after precipitation with an ethanol-benzene mixture were completely soluble in water. In 58 out of 64 patients with cystic fibrosis of the pancreas a considerable part of the precipitated mucoproteins was not soluble in water. This water-insoluble fraction could not be brought into solution by the action of trypsin, but dissolves in 1N NaOH after heating. The water-insoluble mucoprotein was present in the duodenal contents of all patients with cystic fibrosis of the pancreas who also had pancreatic achylia, and in 8 of 14 patients with cystic fibrosis of the pancreas who had retained a significant degree of pancreatic function. Absence of a water-insoluble mucoprotein from the duodenal contents of 6 of the 64 children in whom the diagnosis of cystic fibrosis of the pancreas was established may be explained on the variablity of involvement in this disease. The fact that a water-insoluble mucoprotein was recovered from the duodenal contents of three patients in whom the diagnosis of cystic fibrosis of the pancreas could not be established calls for additional observation; it is still possible that some or all of these three cases actually have this disease in an unrecognized form. Complete correlation has not been demonstrable between the presence of water-insoluble mucoprotein in the duodenal contents and the fully established clinical and laboratory picture of cystic fibrosis of the pancreas. Lack of complete correlation does not interfere to an important degree with the usefulness of the determination of the solubility of the mucoprotein fraction of the duodenal content as a diagnostic measure.