Interaction between leukocytes and serum plasminogen: An essential mechanism in peripheral blood fibrinolytic activity

Publisher Website
Google Scholar
Abstract
Intense fibrinolytic activity (FA) by granulocytes, mononuclear adherent cells, and natural killer (NK) cells was demonstrated by using 125I‐fibrin‐coated wells. This FA was greatly dependent on serum plasminogen, provided that serum inhibitors were destroyed by heating at 56°C. Using monoclonal antibodies, it was also observed that these leukocytes produce urokinase and that this enzyme is secreted during adhesion by mononuclear adherent cells and during the cytotoxicity reaction against neoplastic cells by NK cells. Since cell intactness is necessary for leukocyte‐serum interaction, stress is placed on the membrane function. We conclude that leukocytes are essential in peripheral blood FA and that transport of urokinase by circulating cells, inside their cytoplasm, could offset its lack of affinity for fibrin and thus avoid undesirable systemic effects.