[Immunohistochemistry of cytokeratin expression in human blood vessel endothelia with special reference to synovial connective tissue].

41 tissue samples derived from the synovia, epidermis, and other organs were studied immunohistochemically using monoclonal antibodies against intermediate filaments. We observed a coexpression of cytokeratin and vimentin in endothelia of small blood vessels preferably enriched in locations with enhanced fluid transport and processes of ultrafiltration via endothelial cells (synovial tissue, ganglion). The presence of cytokeratin 18 in endothelial cells has been confirmed by gel-electrophoresis with immunoblotting. In many cases, the coexpression of cytokeratin and vimentin reveals a correlation to the secretion of simply and epithelially differentiated cells as could be demonstrated for other tissue structures in previous studies. The increased expression of cytokeratins in endothelia of ganglion walls is discussed in relation to synovia-like misfunction of the joint connective tissue.