The relationship between von Willebrand factor antigen and fibronectin in human plasma, endothelial cells and fibroblasts in culture.
The distribution of von Willebrand factor antigen (vWFAg) and fibronectin (Fn) in endothelial cells and in fibroblasts in culture was examined using immunohistological methods. Extracellular matrices were studied after removal of cells by mild hypotonic lysis. Co-distribution of these antigens was also examined after culture of fibroblasts in the presence of endothelial cell conditioned medium or of exogenous vWFAg. The presence of intracellular vWFAg and its association with extracellular Fn in confluent endothelial cells was confirmed. Furthermore, both antigens were detected in matrices from fibroblasts grown in the presence of human plasma and endothelial cell medium. vWFAg was not found, however, in the absence of endothelial cell conditioned medium or in experiments using human serum in place of plasma. Cross-linking of vWFAg was examined using quantitative and qualitative electrophoretic methods. Levels of vWFAg in serum from patients with severe Haemophilia A were approximately 50% of those found in the corresponding plasma. Furthermore, vWFAg was reduced to similar levels in serum from normal blood to which heparin was added. The lowest levels of vWFAg were found in the presence of sufficient heparin to totally inhibit the formation of fibrin. In contrast, levels of Fn remained unchanged in these circumstances. The results did not support the view that vWFAg was cross-linked to Fn in plasma by thrombin-activated factor XIII. In addition, immunoelectrophoresis of cultured endothelial cell products did not demonstrate cross-linking of vWFAg to Fn. The data are consistent with the concept that deposition of vWFAg on the subendothelium is dependent on viable endothelial cells or on another product of these cells.
D001777:Blood Coagulation / Q000187:drug effects; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004727:Endothelium / Q000032:analysis; D005347:Fibroblasts / Q000032:analysis; D005353:Fibronectins / Q000032:analysis* / Q000097:blood; D005455:Fluorescent Antibody Technique; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D014841:von Willebrand Factor / Q000032:analysis*
D003432:Cross-Linking Reagents; D005353:Fibronectins; D014841:von Willebrand Factor; D006493:Heparin