CD40-induced countercurrent conduits for tumor escape or elimination?

CD40--which is expressed on endothelial cells and antigen-presenting cells, such as B cells, macrophages and dendritic cells--is a glycoprotein receptor for T cell-expressed CD40-ligand. CD40 signaling leads to production of both pro-inflammatory and anti-inflammatory mediators. Some of these mediators, such as vascular endothelial growth factor, help in angiogenesis, forming new capillaries. Although these capillaries can function as conduits for tumor-cell metastasis, these same vessels can also be a gateway for entry of activated anti-tumor effector cells that eliminate tumors. How such countercurrent processes can be turned in favor of anti-tumor immunity remains to be shown.