DEPRESSION OF PHAGOCYTOSIS BY PLASMIN DEGRADATION PRODUCTS OF PLASMA FIBRONECTIN

  • 1 January 1981
    • journal article
    • research article
    • Vol. 98  (2) , 263-271
Abstract
Disseminated intravascular coagulation was previously shown to cause a depression in RE [reticuloendothelial] function. Fibronectin, a high MW surface-binding glycoprotein, is known to modulate RE function by facilitating opsonic activity and is sensitive to proteolytic cleavage by plasmin, yielding FNDP [fibronectin degradation products]. Isolated FNDP, generated in vitro by incubation with plasmin, apparently can depress phagocytosis in vivo as well as in vitro. Phagocytosis in rats was determined by a clearance technique employing 51Cr-RBC [red blood cell] and in vitro by employing a monolayer of peritoneal exudate macrophages. The in vivo studies demonstrated significantly reduced hepatic phagocytosis after the injection of FNDP and delayed clearance of injected test particles. Macrophage uptake in vitro, supported by either normal rat serum or purified fibronectin, was significantly reduced when incubated with FNDP. Depression of the RE system and phagocytosis during intravascular coagulation may be mediated in part by the formation of plasmin degradation products of plasma fibronectin.