Publication Date:
2005-11-16
Description:
Von Willebrand Factor (VWF) is unable to interact spontaneously with platelets under physiological conditions. To induce this interaction, a conversion of the VWF A1-domain into a Glycoprotein Ibα (GpIbα)-binding conformation is required. We recently described a nanobody, designated AU/VWFa-11 that preferentially recognizes the GpIbα-binding conformation (Hulstein et al. 2005 Blood, in press). Using an AU/VWFa-11 based immunosorbant assay, we found that the active form of VWF circulates in VWD type 2B and Thrombotic Thrombocytopenic Purpura. Although these diseases have different phenotypical appearances, both are characterized by thrombocytopenia. Another disease associated with a low platelet count is HELLP (hemolysis, elevated liver enzymes and low platelets) syndrome, a severe form of preeclampsia that compromises pregnancy. In this study, we have compared the levels of activated VWF in the plasma of healthy pregnant women (n=9), patients suffering from preeclampsia (n=6) and patients with HELLP syndrome (n=14) at similar gestational age. In HELLP syndrome, the levels of activated VWF were increased 1.8-fold compared to healthy volunteers (p=0.0001). Moreover, these levels were also increased 1.5-fold compared to the patients suffering from preeclampsia. In order to get insight into the origin of the increased activated VWF levels, a number of other parameters were determined. VWF antigen levels were found to be increased in normal pregnancy (165% ± 32.5), as expected. In preeclampsia and HELLP syndrome these levels were even further increased (178% ± 89.8 and 338% ± 89.3, respectively). In healthy pregnant women and in preeclampsia, VWF propeptide levels were concomitantly increased. In contrast, in HELLP syndrome propeptide levels were increased up to 3-fold compared to propeptide levels in healthy pregnant women (p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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