On the role of the pancreatic secretory trypsin inhibitor as an inactivator of trypsin-alpha 2-macroglobulin complexes in acute pancreatitis.
High levels of immunoreactive pancreatic secretory trypsin inhibitor (PSTI) were demonstrated in the serum and peritoneal exudates of patients suffering from acute pancreatitis. Trypsin-like immunoreactivity in these fluids was found in complex with alpha 1-antitrypsin and in complex with alpha 2-macroglobulin and also as a free peak correlating to free trypsin(ogen). No trypsin-PSTI complexes or PSTI were demonstrated in the macroglobulin fraction of the peritoneal exudates. Saturated and partially saturated trypsin-alpha 2-macroglobulin complexes were prepared in vitro. PSTI was able to partially inhibit the BzArgNan-cleaving activity of both types of complexes in a slow dose-dependent non-linear reaction. Equilibrium was reached in each case within 1 h, but total inhibition was not reached even with large amounts of PSTI. Partially saturated trypsin-alpha 2-macroglobulin complexes were inhibited more readily than saturated complexes. The results support the concept of PSTI acting as a strictly local inhibitor of trypsin in compartments lacking plasma protease inhibitors.
D000208:Acute Disease; D002850:Chromatography, Gel; D005122:Exudates and Transudates / Q000201:enzymology; D006801:Humans; D007120:Immunochemistry; D010195:Pancreatitis / Q000201:enzymology*; D014357:Trypsin / Q000097:blood; D014359:Trypsin Inhibitor, Kazal Pancreatic / Q000097:blood*; D014361:Trypsin Inhibitors / Q000097:blood*; D000511:alpha-Macroglobulins / Q000037:antagonists & inhibitors*
D014361:Trypsin Inhibitors; C028939:alpha-2-macroglobulin-trypsin complex; D000511:alpha-Macroglobulins; D014359:Trypsin Inhibitor, Kazal Pancreatic; D014357:Trypsin