Plasma proteinase inhibitors in Morris hepatoma-bearing rats: changes in the blood level and synthesis in tissue slices.

The antiproteinase activities against trypsin, chymotrypsin, elastase, papain and rat leucocyte proteinases were determined in plasma from control and Morris hepatoma-bearing rats. Bovine trypsin and chymotrypsin were similarly inhibited by the two types of plasma whereas porcine pancreatic elastase, papain and rat leucocyte neutral proteinases were more efficiently inhibited by plasma from tumour-bearing rats. The increased plasma concentrations of some proteinase inhibitors, as determined by rocket immunoelectrophoresis, are suggested to be responsible for the observed differences in inhibition. The highest increases in plasma of tumour-bearing rats were observed for alpha 2-macroglobulin and alpha 1-acute-phase globulin. The synthesis and secretion of six proteinase inhibitors: antithrombin III, alpha 1-proteinase inhibitor, alpha 1-macroglobulin, alpha 2-macroglobulin, alpha 1-acute-phase globulin and haptoglobin, as well as albumin, were measured in tissue slices from rat liver and Morris hepatoma after incubation with [14C]leucine. Local inflammation inflicted upon the tumour-bearing rats increased formation of acute-phase proteins in liver slices but not in hepatoma slices.