AOC3 and acute graft versus host disease: Based on these reports, Mukai S, et al. studied the following: (1) the prevention of immune cell migration to tissues alleviates acute GVHD (aGVHD) and cGVHD, (2) the increased expression of VAP-1 is involved in the pathogenesis of both types of GVHD, and (3) the inhibition of VAP-1 could be an efficacious treatment for the two types of GVHD in a mouse model.