This antibody reacts with human von
Willebrand factor. Traces of contaminating antibodies have been removed by
solid-phase absorption with human plasma proteins. This protein has functional
binding domains to platelet glycoprotein Ib, glycoprotein IIb/IIIa, collagen and
heparin. The Factor VIII (Von Willebrand Factor) is synthesized by endothelial
cells and stored in the Weibel-Palade granules. This antibody reacts
specifically with the endothelial cells of both normal and reactive, and
neoplastic blood and lymphatic vessels and a finely granular cytoplasmic
staining. It also reacts with endocardium, platelets, and megakaryocytes. Factor
VIII has been shown most useful in marking and identifying normal endothelial
cells of their corresponding neoplasms. However, because not all endothelial
cells synthesize and/or store the molecule, this antibody will mark
approximately 70% of tumors of vascular origin. It is therefore recommended that
both CD34 and Factor VIII be used together as a panel. Staining for factor VIII
related antigen has also been used to measure angiogenesis and has been shown in
some studies to predict tumor
recurrence.