Induction of tissue factor (TF) activity by recombinant LIGHT in human endothelial cells. Endothelial cells were stimulated with isolated soluble LIGHT, harvested after 6 hours and assayed for procoagulant activity as described under "Materials and Methods". LIGHT induced a marked up-regulation of tissue factor in endothelial cells. TF activity of each sample was determined based on comparison with a standard curve established with known amounts of recombinant TF. The data represent the mean of three independent experiments performed (Figure 5D). ***P < 0.0005 vs stimulated cells without bocking antibody.