Immunoreactive trypsin in serum and peritoneal fluid in acute pancreatitis.

High levels of immunoreactive cathodal trypsin are shown to be present in serum and peritoneal fluid in acute pancreatitis. The immunoreactive material is contained in two fractions with different molecular weights: free trypsinogen and trypsin in complex with protease inhibitors, mainly alpha1-antitrypsin. The presence of trypsin in complex with protease inhibitors indicates the formation of active trypsin during acute pancreatitis.