Increase in permeability of human endothelial cell monolayer by recombinant human lymphotoxin

The effect of lymphotoxin (LT) on transendothelial permeability was examined using in vitro human endothelial cell (EC) culture system. To assess permeability, we measured the movement of human IgG labeled with horseradish peroxidase (HRP-huIgG) across an EC monolayer cultured on a fibronectin and collagen-coated membrane. LT increases the permeability dose dependently within 16 hours. Similar results were obtained with tumor necrosis factor (TNF)-alpha. The results suggest that increase in vascular permeability by LT and TNF-alpha plays an important role in initiating hemorrhagic necrosis of tumors in vivo.