 This research study is to determine, if administration of the drug ganciclovir to the recipient, after intravenous infusion of the genetically modified cells lymphocytes into the recipient, will reduce or even eliminate a life threatening complication of allogeneic transplantation, called graft versus host disease GvHD. The drug ganciclovir will kill the infused genetically modified donor cells lymphocytes so they cannot cause GvHD. 