Endothelial cell anergy

Endothelial cell anergy is a condition during the process of angiogenesis, where endothelial cells, the cells that line the inside of blood vessels, can no longer respond to inflammatory cytokines. These cytokines are necessary to induce the expression of cell adhesion molecules to allow leukocyte infiltration from the blood into the tissue at places of inflammation, such as a tumor. This condition, which protects the tumor from the immune system, is the result of exposure to angiogenic growth factors.

Next to endothelial cell anergy, there are more vascular mechanisms that contribute to escape from immunity, such as the expression of immune checkpoint molecules (e.g. PD-L1/2) and proteins that can deliver death signals in leukocytes (Fas ligand and galectin-1).