Proteases and protease inhibitor balance in peritonitis with different causes.

Protease activation and protease-antiprotease interactions were sequentially studied in two different groups of patients with peritonitis. The biochemical changes were related to the cause of the disease and to the clinical course. Protease activation and protease inhibitor consumption were most pronounced in the peritoneal fluid, especially in bacterial peritonitis. Plasma changes also indicated activation of the complement, kinin, and fibrinolytic systems and protease inhibitor consumption, especially of alpha 2-macroglobulin and antithrombin III. There was no significant difference between chemical and bacterial peritonitis regarding these plasma changes. Immunohistologic studies showed evidence of active uptake of protease-antiprotease complexes in macrophage-like cells in the peritoneum in both groups. It is concluded that peritonitis results in protease activation and protease inhibitor consumption, especially in the peritoneal fluid. The peritoneum has an active role in the clearance of protease-antiprotease complexes. The intensity, not the type, of the intra-abdominal challenge determines the biochemical changes in peritonitis.