1. Patients receiving allogeneic hematopoietic cell transplantation (HCT) with peripheral blood, bone marrow or cord blood stem cells regardless of initial diagnosis who develop a clinical diagnosis of acute GVHD as defined in Section 2 diagnosed and treated with systemic glucocorticoids within 72 hours prior to enrollment. Biopsy of involved skin and gastrointestinal tract is strongly encouraged, but not required for study entry. For patients with aspartic transaminase (AST) or alanine transaminase (ALT) or Alkaline phosphatase with gamma-glutamyltransferase (GGT) elevations without bilirubin elevation must have a liver biopsy to document GVHD diagnosis. Patients should meet one of the following criteria: