IFNG and graft versus host disease: Apyrase, a soluble ATP diphosphohydrolase (ATPDase), injected during the first week post-transplantation reduced apoptosis and inflammation in target organs and serum IFN-γ, and increased survival in an allogeneic mouse model of GVHD [72,110] indicating a direct role for extracellular ATP in mediating GVHD progression following pre-conditioning and transplantation.