Abstract
Although it has been pointed out by many researchers that the plasmin plays the main role in to lytic ability of the fibrin thrombi in tissues. Thrombi also result from other proteases such as trypsin, chymotrypsin, and cathepsin, etc. When observation was made for changes of Fibrin Degradation Products (FDP) in time variation in patients with Disseminated Intravascular Coagulation Syndrome (DIC) accompanied by hematologic disorders or neoplastic diseases.
We experienced not a few cases where elevated plasmin activity which has been pointed alone can never be responsible. It was found in many of such cases that there was marked elevation in cathepsin activity. In the present study, the fibrinolytic phenomenon was studied in both aspects of general and local fibrinolysis, and resluts of investigation into the role of cathepsin in the latter are reported.
Cathepsin activity is found in 280 patients with various disease, highst in DIC, and high in neoplastic disease, aplastic anemia, chronic nephritis, leukemia, and hemolytic anemia, etc.
A study in autopsy cases of DIC resulted in that fibrin deposits in renal glomeruli and liver sinusoid was noted, non or very little, in many cases where cathepsin activity is high.
This might reflects to some extent local fibrinolysis in the kidney and liver.
In most of patients with acute type of DIC noted an increase in cathepsin activity and FDP levels where significantly higher than those with chronic type.
Moreover, similary tendency was observed in patients, where its prognosis had been poor.
From those results, in patients with DIC, these two parameters were directly proportional to the prognosis.
In the cases of severe tissue injury develops hypoxia locally to make a highly acid enviroment. Since plasmin in an alkaline protease, it has been loose protease activity at pH 6.0 or less, and thus there would be very little possibitity that it lyzes fibrin clot formed in injured tissues. Under such unfavorable conditions, cathepsin of an acid protease would exert fibrinolytic effect on fibrin thrombi.
