Upregulation of monocyte urokinase plasminogen activator receptor during human endotoxemia

The receptor for urokinase-type plasminogen activator (uPAR) (CD87) plays a n important role in leukocyte adhesion and migration. To assess the effect of endotoxin on cellular uPAR, uPAR expression was determined on leukocytes bg fluorescence-activated cell sorter analysis in seven healthy subjects f ollowing intravenous injection of endotoxin (Iot G; 4 ng/kg). Endotoxin ind uced a transient increase in uPAR expression on monocytes, reaching a 92% /- 46% increase over baseline expression after 6 h (P < 0.05). Endotoxin di d not influence uPAR expression on granulocytes, while uPAR remained undete ctable on lymphocytes. Endotoxin also increased soluble uPAR levels in plas ma (P < 0.05). Stimulation of human whole blood with endotoxin or gram-posi tive stimuli in vitro also resulted in an upregulation of monocyte uPAR exp ression. Although tumor necrosis factor alpha (TNF) upregulated monocyte uP AR expression, anti-TNF did not influence the endotoxin-induced increase in monocyte uPAR expression. These data suggest that infectious stimuli may i nfluence monocyte function in vivo by enhancing the expression of uPAR.