-Patients with the following hematologic malignancies (AML, CML, ALL, B cell malignancies, and myelodysplastic syndrome) who have undergone allogeneic stem cell transplantation. There is no limitation on whether myeloablative or non-myeloablative chemotherapy is administered. A 3/6 or greater match is required for patients who have had an allogeneic stem cell transplant.