Effect of dextran on factor VIII/von Willebrand factor structure and function.

Area of Science:

• Hematology
• Clinical Pharmacology

Background:

• Dextran 70 is a plasma volume expander.
• Its effects on hemostatic factors, particularly Factor VIII and von Willebrand factor (vWF), are not fully understood.

Purpose of the Study:

• To investigate the impact of Dextran 70 infusion on Factor VIII and vWF parameters in healthy individuals.
• To characterize changes in vWF multimeric structure and platelet function post-infusion.

Main Methods:

• Analysis of Factor VIII procoagulant activity, Factor VIII-related antigen, and ristocetin cofactor activity before and after Dextran 70 infusion.
• Assessment of ristocetin-induced platelet agglutination (RIPA) in platelet-rich plasma (PRP).
• Multimeric analysis of von Willebrand factor (vWF).

Main Results:

• A significant decrease in Factor VIII/vWF activities and antigen levels was observed, peaking at six hours post-infusion.
• The reduction in vWF levels did not correlate with hemodilution.
• vWF multimeric analysis revealed a progressive loss of all multimers, with larger multimers affected most significantly.
• RIPA and vWF triplet structure remained unchanged; in vitro incubation showed no direct effect of dextran.

Conclusions:

• Dextran 70 administration alters Factor VIII and von Willebrand factor levels and structure in vivo.
• The observed changes in vWF, particularly the loss of large multimers, resemble findings in von Willebrand disease subtype Ib.
• Dextran 70's effects appear to be systemic rather than a direct interaction with plasma components in vitro.