von Willebrand factor antigen levels in Kaposi's sarcoma

Markers of Coagulation and Angiogenesis in Cancer-Associated Venous Thromboembolism

Purpose: We sought to determine whether venous thromboembolism in cancer patients is associated with aberrant plasma levels of hemostatic and angiogenic factors.

Patients and Methods: Peripheral blood was collected before anticoagulant therapy from cancer patients with acute deep venous thrombosis (DVT; DVT + cancer group, n = 32), those without DVT (cancer control group, n = 36), and patients with acute DVT but no cancer (DVT control group, n = 58). Plasma assays of activation and inhibition of coagulation and fibrinolysis, as well as angiogenesis activation, were then performed.

Results: Median levels of thrombin-antithrombin complex, prothrombin fragments 1 + 2, and von Willebrand factor antigen were significantly greater in the DVT + cancer group than in the cancer control and DVT control groups (17.8 ng/mL v 4.6 ng/mL and 9.8 ng/mL, P = .0001 and P = .003, respectively; 3.65 nmol/L v 1.60 nmol/L and 2.71 nmol/L, P < .0001 and P = .011, respectively; and 4.04 U/mL v 2.26 U/mL and 2.06 U/mL, P < .0001, respectively). Median levels of tissue-type plasminogen activator were also significantly higher, while protein C activity was lower in the DVT + cancer group than in the DVT control group (14.6 ng/mL v 9.50 ng/mL, respectively, P = .0005; 0.89 U/mL v 1.11 U/mL, respectively, P = .0008).

Conclusion: These data not only support prior observations of coagulation activation in patients with malignancy, but also provide new evidence for enhanced coagulation activation in the setting of acute venous thromboembolism in cancer. Future prospective studies are warranted to determine whether these and other potential markers of hypercoagulability may help to identify cancer patients at highest risk for venous thromboembolism.

Quantitative and qualitative assessment of plasma von Willebrand factor in classic Kaposi's sarcoma

BACKGROUND

von Willebrand factor (vWF) is synthesized almost exclusively by endothelial cells and is stored there as ultra-high-molecular-weight multimers. The vWF multimers that are detected in the plasma are smaller than those stored within the endothelium. In two previous studies, comprising small series of cases with classic Kaposi's sarcoma (KS), an endothelium-derived tumor, increased levels of plasma von Willebrand factor antigen (VWF:Ag, the antigenic structure) were reported, suggesting that vWF:Ag may be a marker of endothelium proliferation.

OBJECTIVE

Our purpose was to investigate the quantitative as well as qualitative alterations of plasma vWF in a large series of patients with classic KS at various stages of the disease.

METHODS

Levels of plasma vWF:Ag were studied in 38 patients with classic KS confined to the skin at various stages of the disease and compared with a control group. Thirty-three patients had active KS (i.e., with skin lesions) and five were in remission. In five patients with active KS multimeric analysis of plasma vWF was also performed.

RESULTS

The levels of vWF:Ag were significantly higher among KS patients than in the control group (n = 29, p < 0.01). Levels of vWF:Ag were also significantly higher in patients with active disease as compared with those in remission (p < 0.05). No correlation was found between vWF:Ag levels and the extent of KS. Analysis of the multimeric pattern of plasma vWF showed enhanced staining of all bands, particularly the intermediate and high molecular weight forms, which resemble the endothelial forms as opposed to normal circulating vWF multimers.

CONCLUSION

Quantitative as well as qualitative alterations in plasma vWF were found in patients with KS, which may reflect the destruction or activation of endothelial cells within the lesions. vWF:Ag may serve as a marker of disease activity in classic KS; however, it is not a good marker for the extent of the disease.

Ultrastructural localization of alpha-L-fucose, factor VIII related antigen and vimentin in endothelial cells of human skin blood vessels using the low temperature embedding technique with Lowicryl K4M

The present study was performed to investigate the ultrastructural localization of the binding sites of the lectin Ulex europaeus agglutinin, Type I (UEA) and the antibody against factor VIII related antigen (F VIII RAG), both widely used as vascular markers in human skin capillaries at light microscopy level. In addition the ultrastructural localization of vimentin, the major protein of the endothelial intermediate filaments, was demonstrated in human vascular endothelial cells (EC) in situ. The low temperature postembedding technique with Lowicryl K4M with subsequent application of gold labelled antibodies provided both well preserved antigenicity and morphology. The antigenic site of UEA, alpha-L-fucose containing glycohydrate residues, was primarily found in or near the luminal plasma membrane of EC. Gold particles representing the sites of F VII RAG were located in the Weibel-Palade bodies (WPB) of EC. The ultrastructural staining pattern of the anti-vimentin antibody showed an exclusive labelling of the intermediate filaments of EC.

Histogenesis of Kaposi's sarcoma and angiosarcoma of the face and the scalp

This study reviews data on the histogenesis of Kaposi's sarcoma and angiosarcoma derived from clinical features, histology, electron microscopy, enzyme histochemistry, and immunochemistry of both diseases. Their hemorrhagic clinical appearance contrasts the predominantly lymphatic histologic features of vessels in early lesions. Investigations performed to resolve the debate whether these tumors arise from blood vessel or lymphatic endothelium show remarkably similar results for both conditions. Electron microscopy reveals Weibel - Palade bodies in a minority of cases, but features consistent with less well-differentiated blood vessel endothelium may be seen in a greater proportion of tumors. Enzyme histochemistry generally shows absence of adenosine triphosphatase and alkaline phosphatase in tumor cells; a pattern of enzymes similar to that found in normal lymphatic endothelium. Conflicting data arises from the large number of immunohistochemical studies performed on both conditions. Factor VIII-related antigen and Ulex europaeus agglutinin-I have been most frequently employed, but the specificity of these agents for blood vessel endothelium is debatable. Panendothelial markers show consistent labeling of both tumors, but marker studies employing a wide range of monoclonal antibodies specific for blood vessel endothelium have shown occasional positive labeling of tumor cells. A number of studies have claimed absence of labeling with specific blood vessel monoclonal antibodies, but at present no study employing a specific marker for lymphatic endothelium has been reported. Although the demonstration of specific markers for blood vessel endothelium in these tumors has been variable, the data would be compatible with lesions arising from undifferentiated stem cells that proliferate with varying degrees of differentiation toward blood vessel endothelium. An alternative hypothesis for the histogenesis of Kaposi's sarcoma would be one of multicentric hyperplasia containing lymphatic venular anastamoses with elements of both lymphatic and blood vessel endothelium.