Non-Ablative Allo HSCT For Hematologic Malignancies or SAA

DISEASE CHARACTERISTICS: Histologically proven high-risk hematologic malignancy Acute non-lymphocytic leukemia (ANLL) after induction failure, or in first complete remission (CR) with high-risk features, including any of the following: Stem cell or biphenotypic classification (AML-M0) Erythroleukemia (AML-M6) Acute megakaryocytic leukemia (AML-M7) Cytogenetic markers indicative of poor prognosis Failure to achieve CR after standard induction therapy Acute lymphocytic leukemia (ALL) or ANLL in relapse or second or subsequent remission Chronic myelogenous leukemia (CML) in chronic or accelerated phase Patients with CML in blast crisis are eligible after reinduction chemotherapy places them in chronic phase High-risk ALL in first CR with high risk defined by presence of t(4;11), t(9;22) translocation, hyperleukocytosis (initial WBC greater than 30,000/mm^3), or failure to achieve CR by day 28 after standard induction No T-cell ALL or t(8;14) positive B-cell ALL in first remission with hyperleukocytosis Myelodysplastic syndrome by peripheral blood smear and bone marrow examination Refractory to medical management OR Cytogenetic abnormalities predictive of transformation into acute leukemia including 5q-, 7q-, monosomy 7, and trisomy 8 OR Evidence of evolution to AML (e.g., refractory anemia with excess blasts (RAEB) or RAEB in transformation) Multiple myeloma, non-Hodgkin's lymphoma (NHL), ANLL, or ALL with recurrent disease after autologous stem cell transplantation (SCT) At least 3 months since prior autologous SCT Hodgkin's lymphoma, NHL, or multiple myeloma beyond first CR or primary induction failures whose disease has demonstrated sensitivity to pre-transplantation cytoreduction (defined as greater than 50% reduction in tumor burden) Mantle zone NHL allowed after induction therapy Myeloproliferative disorder that is non-responsive to medical management and requires allografting, unless evidence of grade 3 or worse myelofibrosis on marrow biopsy OR Histologically proven acquired severe aplastic anemia (SAA) that is recurrent or unresponsive after anti-thymocyte globulin and/or cyclosporine SAA defined by at least 2 of the following conditions: Granulocyte count less than 500/mm^3 Platelet count less than 20,000/mm^3 Absolute reticulocyte count less than 20,000/mm^3 after correction for hematocrit Ineligible for full ablative conditioning due to any of the following conditions: Prior extensive therapy (more than 2 salvage chemotherapy regimens and/or autologous transplantation) Over age 55 OR Under age 55 with comorbid disease (e.g., suboptimal cardiac, pulmonary, or renal function and/or prior life-threatening infection) HLA-A, B, and DR phenotypically identical sibling donor OR HLA-A, B, and DR identical genetically matched unrelated donor No ANLL in first CR (less than 5% blasts in marrow) with translocations t(8;21) and inv(16) unless failed first-line induction therapy OR No ANLL in first CR (less than 5% blasts in marrow) with translocations t(15;17) abnormality unless failed first-line induction therapy OR molecular evidence of persistent disease No active CNS disease PATIENT CHARACTERISTICS: Age: 0 to 70 Performance status: Zubrod 0-1 Karnofsky 80-100% Life expectancy: At least 3 months Hematopoietic: See Disease Characteristics Hepatic: ALT/AST no greater than 4 times normal Bilirubin no greater than 2.0 mg/dL Renal: See Disease Characteristics Creatinine clearance at least 50 mL/min Cardiovascular: See Disease Characteristics Shortening fraction or ejection fraction at least 40% of normal for age by echocardiogram or radionuclide scan No clinically significant comorbid illnesses (e.g., myocardial infarction or cerebrovascular accident) Pulmonary: See Disease Characteristics FVC and FEV_1 at least 60% of predicted for age DLCO at least 60% of predicted for adults Other: No severe neurosensory symptoms (i.e., peripheral neuropathy) HIV negative Active infection allowed if controlled by appropriate drug therapy Not pregnant or nursing Negative pregnancy test PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics Chemotherapy: See Disease Characteristics Endocrine therapy: Not specified Radiotherapy: Not specified Surgery: Not specified Other: Recovered from prior therapy No concurrent investigational agents unless approved by protocol investigators