POLAR EXPRESSION OF TISSUE FACTOR IN HUMAN UMBILICAL VEIN ENDOTHELIAL-CELLS

Endothelial cells grown on filters developed junctional complexes that reduced diffusional transport and increased electrical resistance ove r the cell layer. Induction of tissue factor by recombinant interleuki n-lp led to a highly polarized tissue factor expression on the apical cell surface only. After prolonged growth to allow deposition of matri x, removal of the endothelial cells by collagenase or by 0.1 mol/L NH4 OH left behind some cellular material as well as tissue factor, which was only detectable in the upper compartment. A human bladder carcinom a cell line, which does not form tight junctions and expresses tissue factor constitutively, showed essentially no polarity. Endothelial cel l secretory compounds like von Willebrand factor, tissue plasminogen a ctivator, and plasminogen activator inhibitor-1 were constitutively re leased to both sides. The added secretion due to recombinant interleuk in-1 beta stimulation of the endothelial cells observed for von Willeb rand factor and tissue plasminogen activator was, however, localized t o the apical surface. The availability of tissue factor on the luminal surface of endothelial cells, ie, allowing contact with factor VII in the flowing blood, has potentially very significant pathophysiologica l consequences.