Expression Of Factor VIII-related Antigen Research Articles

Adenomatoid tumours: a mucin histochemical and immunohistochemical study.

We have examined 16 cases of adenomatoid tumour using a panel of monoclonal and polyclonal antibodies and also stained them for the presence of hyaluronidase-sensitive alcianophilic material. Fourteen cases expressed cytokeratins and a proportion of these also expressed S-100 protein, neuron-specific enolase, vimentin, and human milk fat globule protein 2. The same 14 cases also showed hyaluronidase-sensitive staining with alcian blue. No expression of factor VIII-related antigen was seen in these cases. We conclude that this provides further evidence of a mesothelial origin of these tumours. The remaining two cases did not express cytokeratins and no hyaluronidase-sensitive staining with alcian blue was seen. They did however express factor VIII-related antigen. Although they were morphologically indistinguishable from the other 14 cases, we suggest that they should be more properly regarded as angiomas.

Endothelin-Secreting Tumor

Recently, we have reported two cases with endothelin (ET)-secreting tumor presenting with hypertension and elevated plasma endothelin-1 (ET-1) levels. The present study examines the histopathology of the ET-secreting tumor in one of these cases. The neoplasm was located in the skin and microscopically characterized as a malignant hemangioendothelioma by remarkable intravascular proliferations of atypical endothelium with the expression of Factor VIII-related antigen in the tumor cells. The tumor enlarged rapidly with rising ET-1 and blood pressure levels. The ET-1 content and its messenger RNA expression in the tumor extract were higher than those from normal parts of skin. ET-1 may play a pathophysiological role in patients with ET-secreting malignant hemangioendothelioma.

Long-term culture and characterization of human limbal microvascular endothelial cells

Human limbal explants obtained from 44 eyebank donors were cultured in medium 199 supplemented with 20% fetal bovine serum, vascular endothelial cell growth supplement and heparin. Cells grew abundantly out of the explants. They initially formed a ‘cobblestone’ patterned monolayer but later exhibited an elongated morphology with growth in parallel bundles. These cells could be passaged at least nine times and were identified throughout the consecutive passages as microvascular endothelial cells by the expression of factor VIII-related antigen, laminin and of the H determinant of ABO blood groups. As expected from vascular endothelial cells, flow cytometric analysis demonstrated a strong expression of class I histocompatibility antigens and a weaker expression of class II antigens. Class II antigen expression was enhanced by culturing the cells in the presence of immune interferon. These cells produced immunoreactive interleukin-1, mainly of the α type, under endotoxin stimulation. Limbal microvascular cells could be useful to study corneal angiogenesis. Furthermore, long-term culture of limbal cadaveric tissue can potentially be used to characterize donor-specific immunologic responses in corneal graft recipients.

Specific antigen and organelle expression of a long-term rhesus endothelial cell line.

A long-term culture of a spontaneously transformed endothelial cell line derived from the choroid-retina of a rhesus macaque fetus is reported. It has been carried in vitro by serial propagation more than 548 passages in 17 yr. Cells were identified as being of endothelial origin by cellular morphology, growth pattern, ultrastructure, immunocytochemistry (immunofluorescence and immunoperoxidase), and immunodiffusion. The transformants are characterized by an infinite life span, a changed expression of Factor VIII-related antigen, and chromosomal aberrations. Throughout long-term serial passages and after repeated freeze-storage, thawing, and reculture the cells retain the specific organelles, Weibel-Palade bodies, and most of the other characteristic morphologic features. For this long-term cultured endothelial cell line, Weibel-Palade bodies seem to be a more reliable marker than Factor VIII-related antigen.

Expression of Fibronectin, Laminin, and Factor VIII-Related Antigen During Development of the Human Cutaneous Microvasculature

The regulation of angiogenesis during human skin development is poorly understood. Since fibronectin is involved in cell movement and organization during embryogenesis and morphogenesis in a variety of species, we investigated the expression of fibronectin and factor VIII-related antigen, a marker for endothelial cells, at various stages in the development of the human cutaneous microvasculature. Skin specimens were obtained from 4 human fetuses during the second trimester (14-18 weeks), from newborn foreskins, and from consenting normal adults. Cryostat sections were stained with both fluorescein-conjugated rabbit antihuman fibronectin and rhodamine-conjugated goat antihuman factor VIII-related antigen. Expression of fibronectin in the microvasculature was striking in fetal skin but became progressively less prominent with maturation. Fibronectin appeared in fetal blood vessels as a bright continuous linear array, in neonatal blood vessels as a bright interrupted linear and speckled array, and in adult blood vessels as a sparse interrupted linear and speckled array. In contrast, expression of factor VIII-related antigen by the endothelium became more prominent with the degree of maturation of the microvasculature. Granular factor VIII-related antigen staining was scant in the newly forming blood vessels of fetal skin, bright but focal in the microvasculature of newborn skin, and intense and almost confluent in the blood vessels of adult skin. Although expression of fibronectin and factor VIII-related antigen changed, expression of laminin was consistent throughout development. Staining of the same skin specimens with fluorescein-conjugated sheep antihuman laminin produced a bright continuous linear pattern in all blood vessels. The reciprocal relationship manifested by intense fibronectin staining during human blood vessel development and prominent factor VIII-related antigen staining in mature blood vessels supports the hypotheses that fibronectin plays a role in human blood vessel modulation and morphogenesis, and that factor VIII-related antigen is a marker for endothelial cell differentiation.

Permanent cell line expressing human factor VIII-related antigen established by hybridization.

A permanent human cell line, EA . hy 926, has been established that expresses at least one highly differentiated function of vascular endothelium, factor VIII-related antigen. This line was derived by fusing human umbilical vein endothelial cells with the permanent human cell line A549. Hybrid cells that survived in selective medium had more chromosomes than either progenitor cell type and included a marker chromosome from the A549 line. Factor VIII-related antigen can be identified intracellularly in the hybrids by immunofluorescence and accumulates in the culture fluid. Expression of factor VIII-related antigen by these hybrid cells has been maintained for more than 100 cumulative population doublings, including more than 50 passages and three cloning steps. This is evidence that EA . hy 926 represents a permanent line.

Expression of factor VIII-related antigen and ulex lectin binding sites in endothelial cells during long-term culture

The expression of factor VIII-related antigen (VIIIR:Ag) and the binding of Ulex Europaeus I lectin, a newly introduced endothelial marker, were studied upon repeated subculture of human umbilical vein endothelial cells. In primary culture, all cells showed a characteristic, finely granular cytoplasmic VIIIR:Ag-specific staining and binding of UEA I both to cell surface membrane and to a cytoplasmic reticular juxtanuclear structure representing the Golgi apparatus. After subculture, the number of VIIIR:Ag-positive cytoplasmic granules decreased and gradually up to 50 % of the cells became negative for this antigen, while still showing a uniform surface binding of UEA I lectin. In surface staining, VIIIR:Ag did not show any membrane-like localization but was distinctly associated with fibronectin-containing pericellular matrix fibers at all culture stages. UEA I lectin showed only a homogenous cell membrane staining.