Peritoneal fluids from patients with diffuse peritonitis secondary to perforation of the appendix contained large quantities of collagenase and elastase. The enzymes, which existed in the form of complexes with plasma protease inhibitors, may be released from the granulocytes. The 2 enzymes had linked almost half of the .alpha.1-antitrypsin and four-fifths of the .alpha.2-macroglobulin in the fluid. Evidence that regional defense against protease failed was obtained the C3 component of complement converted. Toxic peptides were released. Recognition of plasma protease inhibitors as an important part of the regional defense against protease also suggested use for therapy. The peritoneum was lavaged postoperatively with fluid that did not contain plasma inhibitors but with volumes large enough to eliminate the accumulation of enzymes from the granulocytes.