Although with lower affinity than VLA-4, α4β7 integrin can bind VCAM-1 (74), and we hypothesize that VCAM-1, which has a high endothelial expression in the CNS during MS and EAE, may represent an alternative endothelial counter-ligand in leptomeningeal vessels for α4β7 integrin expressed on Th17 cells (75).Once migrated through the pial vessel wall, encephalitogenic T cells need to be reactivated by leptomeningeal APCs for acquiring the ability to infiltrate the CNS parenchyma (10, 76). Here, VCAM1 is linked to myeloid sarcoma.