3. Patient must have biopsy-proven Grade I acute GVHD (Appendix A). Biopsy report does not have to be back from Pathology prior to enrollment. Patients whose biopsy for GVHD identifies pathology inconsistent with GVHD will be removed from the study and replaced. However, because GVHD is a clinical diagnosis, biopsies which are non-diagnostic or do not show a clear non-GVHD etiology will not be cause to remove the patient from the study.