Immunohistochemical localization of trypsinogen and trypsin in acute and chronic pancreatitis.

Immunoreactive trypsin was localized with the peroxidase-antiperoxidase technique in normal human pancreatic tissue and in the glands of patients suffering from acute or chronic pancreatitis. In the normal pancreas and in the histologically normal areas of the inflamed pancreas, trypsin was detected in the zymogen granules of acinar cells and in ductal secretory material. During acute pancreatitis, three characteristic changes were observed: (1) separate acinar cell fragments in early lesions; (2) decreased and evenly dispersed staining in necrotic acinar cells, and (3) intensive reaction in plugs in acinar lumina in advanced lesions. In chronic pancreatitis, the localization of trypsin in acinar cells was similar to that in normal pancreas. Some proteinaceous plugs in dilated pancreatic ducts were weakly immunoreactive. The results show that the tissue distribution of immunoreactive trypsin is altered in acute pancreatitis.