Effect of dengue virus on procoagulant and fibrinolytic activities of monocytes.

Some of the fibrinolytic and coagulation enzymes that monocytes produce are urokinase, a plasminogen activator (PA); a PA-specific inhibitor (PAI); and procoagulant activity (PCA), which has been characterized as tissue factor. Dengue infection in vivo is restricted to monocytes; however, it is unknown if dengue-infected monocytes undergo alterations in the production of PA, PAI, and PCA. This issue was addressed in studies in which monocytes were infected in vitro with dengue 2 virus in serum-free medium in the presence of enhancing antibody. No urokinase activity was detected in either control or infected cells or in their supernatants. Infection of monocytes with dengue 2 virus resulted in an almost threefold increase in PAI activity in cells and supernatants. No change in relation to the control was observed in PCA generated by the infected cells. These data indicate that dengue 2 infection enhances the production of PAI from monocytes without altering PA or PCA.