VCAM1 and acute graft versus host disease: Acute GvHD is associated with the up‐regulation of several endothelial cell adhesion molecules such as E‐selectin, P‐selectin, VCAM‐1 and ICAM‐1 in the affected organs in response to the effect of pro‐inflammatory cytokines, favouring donor alloreactive leucocytes to engage the endothelium and extravasate to the target tissue(s).26, 27, 28