OUTLINE: Harvest: Bone marrow and peripheral blood stem cells (PBSC) are harvested from a related 1, 2, or 3 HLA antigen mismatched donor. PBSC are selected for CD34+ cells and T-cells are depleted. Conditioning: Patients undergo total body irradiation twice daily on days -10 to -7 and once on day -6. Patients receive cladribine IV continuously on days -10 to -6; etoposide IV over 2 hours on day -5; and cyclophosphamide IV over 2 hours, antithymocyte globulin (ATG) IV over 10-12 hours, and methylprednisolone IV over 1 hour on days -4 to -2. Transplantation: T-cell depleted PBSC and bone marrow are infused on day 0. Patients receive G-CSF SQ daily beginning on day 0 and continuing until blood counts recover. Graft versus host disease prophylaxis: Patients receive tacrolimus IV every 12 hours beginning on day -2 and continuing orally 4 times a day for 6-12 months at the discretion of the protocol investigator. Patients receive ATG IV over 10-12 hours and methylprednisolone IV over 1 hour on days 5-15 followed by a taper of methylprednisolone. Patients are followed every week through day 100 and then at 6 and 12 months.