Loss of proteinase binding capacity of plasma alpha₂ macroglobulin in some disease conditions

Alpha₂-macroglobulin (MG) levels in terms of proteinase binding capacity in fresh plasma of diabetics (males 183.9±60.3 mg MG/dl, females 173.8±49.7) and viral hepatitis patients (195.2±41.4) were comparable to normal sujbects (males 180.0±28.6, females 213.0±59.6) whereas in renal failure the values were decreased (144.0±30.0) and was found to be increased in nephrotic syndrome (331.5±47.9). MG activity was stable in normals and nephrotic patients in plasma on standing for 12 hr. at 37°C. In other conditions, the proteinase binding capacity was considerably reduced (mean decrease: 51.2% in diabetes, 64.0% in renal failure and 52.6% in viral hepatitis). Concentration of MG determined by immunoelectrophoresis did not however change in diabetic plasma on 12 hr. incubation. It is proposed that proteinases are continously generated in plasma in some disease conditions which bind to MG causing reduction in measured proteinase binding capacity.