Chemokine gradients spare graft endothelium from CD8+ T cell–mediated injury during allograft rejection

T cell-mediated rejection (TCMR) develops after alloantigen-primed T cells migrate into an allograft to cause tissue damage. In contrast to antibody-mediated rejection, which creates lesions in the graft vasculature, injury to the graft vasculature is often limited during TCMR. In this issue of the JCI, Barba et al. investigated the mechanism by which the endothelium is spared from harm caused by graft-infiltrating CD8+ T cells. Endothelial cell protection was due to cell-extrinsic chemokine variations in the environment, rather than cell-intrinsic differences between endothelial and interstitial cells. The CXCL12 gradient in particular facilitated CD8+ T cell movement through the endothelial layer into the graft parenchyma. These findings suggest that targeting the CXCL12 pathway may prevent or alleviate TCMR.