Kinin activation and protease inhibitors in acute pancreatitis in man.

The changes in the protease inhibitors and in the kallikrein-kinin system were analysed in 19 attacks of acute pancreatitis in man and correlated to the severity and clinical course of the disease. Functional alpha 2-macroglobulin was 5% in peritoneal fluid and 32% in blood in severe attacks. Functional Cl inactivator was zero in the peritoneal fluid, while values were normal in blood. High levels of complexes between alpha 1-proteinase inhibitor and trypsin were found during the first 6 days of illness in severe attacks, especially in the peritoneal fluid. Prekallikrein, kininogen and kallikrein inhibition were significantly lower in blood in severe attacks than in moderate or mild attacks. These changes were even more pronounced in the peritoneal fluid, where kallikrein-like activity was above normal, while kininogen and kallikrein inhibition were zero in severe attacks. Both high and low molecular weight kininogen were decreased, denoting an activation also by kininogenases other than plasma kallikrein. In conclusion, kinin activation was demonstrated in acute pancreatitis, especially in the peritoneal fluid. Kinin activation and protease inhibitory activity were closely correlated to the severity and clinical course of the disease. Tryptic activation of the kinin system seems probable at the low alpha 2-macroglobulin levels found in severe attacks, according to our earlier in vitro studies.