Summary
The localization of factor VIII procoagulant antigen (VIII: Ag) and factor VIII von
Willebrand antigen (VWF: Ag) was investigated in human liver, lung, spleen, placenta
and umbilical cord, by an immunoperoxidase technique using an avidin biotin complex
(ABC). Positive staining for VIII: Ag was observed in the endothelial cells of liver
sinusoids, veins and arteries, as well as in the endothelial cells of placenta, lung
and spleen. VWF: Ag was detected in the vascular endothelial cells of all the organs
explored. The staining intensity of both VIII: Ag and VWF: Ag varied in the different
tissues and showed a distinctive pattern of distribution in the liver. VIII: Ag was
also observed in the cytoplasm of dysplastic, foetal-like hepatocytes which infiltrated
one liver specimen. Our results agree with the view that liver endothelial cells are
a major site of Factor VIII (F VIII) storage and secondary release into the circulation.
However, the bright staining intensity of VIII: Ag and VWF: Ag in the lung and placenta
suggests that these two tissues might also be a substantial source of F VIII.
Keywords
Factor VIII - Tissue localization - Immunoenzymohistology