Inability to detect hepatitis B surface antigen (HBsAg) in the duodenum of HBsAg-positive persons.

Incubation of hepatitis B surface antigen (HBsAg)-positive serum with duodenal fluid (DF) of normal persons results in marked reduction of immunoreactivity. This was shown to be caused by: (1) interference with radioimmunoassay (RIA) system and (2) actual destruction of HBsAg. The interference in the RIA system could be counteracted by addition of bovine serum and a reproducible detection system of HBsAg in DF was established. DF of HBsAg-positive persons was negative for HBsAg. One HBsAg carrier who had a partial pancreatectomy for an insulinoma had separate cannulae in his bile and pancreatic ducts. Whereas HBsAg could be detected in bile, it was undetectable in pancreatic juice. Incubation of his pancreatic juice with his bile resulted in disappearance of HBsAg. It appears that a factor present in pancreatic juice, or resulting from the interaction of pancreatic juice and bile, results in disappearance of HBsAg immunoreactivity.