von Willebrand factor

(redirected from VWF antigen)

fac·tor VIII

in the clotting of blood, also known as: antihemophilic factor A (Brinkhous), antihemophilic globulin (1) (Patek and Taylor), antihemophilic globulin A (Cramer), plasma thromboplastin factor (Ratnoff), plasma thromboplastin factor A (Aggeler), thromboplastic plasma component (Shinowara), thromboplastinogen (Quick), prothrombokinase (Feissly), platelet cofactor (Johnson), plasmokinin (Laki), thrombokatilysin (Leggenhager), and proserum prothrombin conversion accelerator. Factor VIII participates in the clotting of the blood by forming a complex with factor IXa, platelets, and calcium and by enzymatically catalyzing the activation of factor X. Deficiency of factor VIII is associated with classic hemophilia A. Factor VIIIC is the coagulant component of factor VIII which, in normal people, circulates in the plasma complexed with Factor VIIIR (von Willebrand factor), the plasma factor VIII-related protein, a large glycoprotein component that is synthesized by endothelial cells and megakaryocytes, and circulates in the plasma where it binds to arteries that have lost their endothelial cell linings, creating a surface to which platelets adhere. Disorders involving factor VIIIR comprise a heterogenous group of abnormalities called von Willebrand disease. A deficiency of factor VIII can lead to impaired blood coagulation.
Farlex Partner Medical Dictionary © Farlex 2012

von Willebrand factor

Hematology A large–> 20,000 kD multimeric molecule composed of ± 200 kD monomers, synthesized by vascular endothelium, megakaryocytes and platelets; vWF's hemostatic efficiency is related to multimer size. See Rocket electrophoresis.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

von Willebrand factor

A plasma protein secreted by endothelial cells that helps platelets to adhere to the damaged lining of blood vessels.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

von Willebrand factor (vWF)

A protein found in the blood that is involved in the process of blood clotting.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
So, vWF antigen reference values should be used which are appropriate for each patient's blood type (35).
The standard diagnostic tests include measurement of total vWF protein (vWF antigen), a vWF activity (such as ristocetin-cofactor activity) and ristocetin-induced platelet aggregation (RIPA), which determine the ability of vWF to bind platelets.
Diagnostic assays include platelet concentration of vWF antigen, an activity test of vWF-platelet binding, and factor VIII activity.
VWF antigen (VWF:Ag) is measured by enzyme-linked immunosorbent assay (ELISA) using anti-human VWF monoclonal antibody (2.2.9) as capture antibody and biotinylated anti-human VWF monoclonal antibody (5.5.72) as detection antibody.
FVIII activity and VWF antigen levels were significantly higher in the AF patient group as compared to the control group in the samples obtained from the FV and from the LA (Figure 1).
Coagulation studies showed a normal PT and PTT and no evidence of Von Willebrand disease (VWF antigen, 107 IU/dL; ristocetin cofactor, 116 IU/dL; FVIII activity, 97 IU/mL).
Further workup with coagulation studies showed decreased factor VIII, vWF antigen, and vWF: ristocetin cofactor assay, and negative Bethesda assay, indicating acquired von Willebrand disease.
Treatment resulted in normalization of VWF antigen level (VWF:Ag), VWF activity (VWF:RCo), and factor VIII activity assay (FVIII activity).
[3] Nonstandard abbreviations: FVIII, factor VIII; PT, prothrombin time; APTT, activated partial thromboplastin time; AT, antithrombin; VWF, von Willebrand factor; VWF:Ag, VWF antigen; VWF:CB, VWF collagen binding; VWF:RCo, VWF ristocetin cofactor activity; FVIII:C, FVIII coagulant activity; FIX:C, FIX coagulant activity; PC-chrom, protein C chromogenic; PS-act, protein S activity; PS-total, protein S total; PS-free, protein S free; PC-clot, PC clotting; [CV.sub.A], analytical variation; [CV.sub.I], within-individual variation; CVG, between-individual variation; EFLM, European Federation for Laboratory Medicine; EQA, external quality assessment.
* Plasma vWF antigen level was assayed by ELISA technique using AsserachromvWF kit (DiagnosticaStago, France).