Immunohistochemical studies on enterokinase producing cells in the biliary tract.

The activation mechanism of pancreatic enzymes refluxing into the biliary tract in the anomalous arrangement of pancreaticobiliary ducts (APBD) remains unclear. In order to elucidate this activation mechanism, an immunohistochemical examination of both bile ducts and gallbladders was carried out on 20 patients with APBD to determine whether or not enterokinase (EK) producing cells exist in the biliary tract, by employing an avidin-biotin-peroxidase complex (ABC) method using a monoclonal antibody, hek-1. Immunoreactive EK was found in the metaplastic epithelium of the bile duct in 2 patients and the gallbladder in one, suggesting that EK production at the metaplastic epithelium is involved in an activation mechanism of pancreatic enzymes refluxing into the biliary tract. The same study was performed on the gallbladders of 62 patients without APBD, which revealed immunoreactive EK in some parts of the metaplastic epithelium of the gallbladder in 2 patients. Thus, in cases of pancreatic juice refluxing into the biliary tract regardless of the presence of APBD, we can not refute the possibility that refluxed pancreatic enzymes may be at least partly activated by EK produced at the metaplastic epithelium.