Inclusion Criteria

DISEASE CHARACTERISTICS:

- Diagnosis of a confirmed hematological malignancy that has relapsed or is at high
risk for relapsing, including any of the following:

- Acute myeloid leukemia (AML) meeting any of the following criteria:

- Antecedent hematologic disorder

- Therapy related

- Primary induction failure

- In first complete remission (CR1) with poor-risk cytogenetics, as defined
by the following:

- del(5q)/-5

- del(7q)/-7

- abn(3q)

- t(6;9)

- del(20q)

- del(17p)

- +13

- Complex karyotype

- t(9;22) = 11q23 rearrangement

- In second complete remission (CR2) or greater

- Acute lymphoblastic leukemia meeting any of the following criteria:

- In CR1 with WBC > 50,000/mm³ at diagnosis

- In CR1 with poor-risk cytogenetics (i.e., t[9;22], t[1;19], t[4;11]) AND
meets at least 1 of the following criteria:

= 19-75 years of age AND received prior high-dose chemotherapy, total-body irradiation
(TBI), or a radiation dose that precludes administration of 12 Gy of TBI = 50-75 years of
age = 19-75 years of age with hematopoietic stem cell transplantation (HSCT) comorbidity
index ≥ 3

- CNS or testicular involvement at diagnosis

- No CR within 4 weeks of initial treatment

- Primary induction failure

- In CR2 or greater

- Myelodysplastic syndromes meeting the following criteria:

- Intermediate-2 or high-risk category as determined by International Prognostic
Scoring System

- Not considered a candidate for intensive or standard chemotherapy or HSCT

- Chronic myelogenous leukemia meeting any of the following criteria:

- First chronic phase AND < 40 years of age

- First chronic phase AND no hematologic response after 3 months of imatinib mesylate
therapy

- First chronic phase AND never achieved a complete cytogenetic response during
imatinib mesylate therapy

- First chronic phase AND loss of previously documented response

- Accelerated phase

- Blast crisis phase

- Chronic myeloproliferative disorder (i.e., polycythemia vera, essential
thrombocythemia, myelofibrosis)

- Bone marrow blasts > 5% and/or other evidence of progression to acute leukemia

- Chronic myelomonocytic leukemia

- Severe aplastic anemia

- Failed prior antithymocyte globulin and cyclosporine immunosuppressive therapy

- Mantle cell lymphoma meeting any of the following criteria:

- In CR1

- In first partial remission (PR1)

- In CR 2 or greater

- In second PR (PR2) or greater

- Indolent non-Hodgkin lymphoma OR chronic lymphocytic leukemia meeting either of
the following criteria:

- In CR 2 or greater

- In PR 2 or greater

- Lymphoblastic lymphoma

- In CR1 or greater

- Must have minimal residual disease as defined by either of the following:

- No more than 5% blasts in blood and/or bone marrow (in patients with acute
leukemia/MDS)

- No bulky adenopathy (> 5 cm masses) and/or < 20% bone marrow involvement by
lymphoma (in patients with lymphoma)

- No progressive disease within 8 weeks of most recent prior therapy OR within 12
weeks of prior autologous HSCT

- No active CNS malignancy (i.e., known positive CSF cytology or parenchymal
lesions visible by CT scan or MRI)

- HLA-matched unrelated peripheral blood stem cell donor available

- Meets the University of Nebraska Medical Center's or the National Marrow
Donor Program's criteria for donors

- Matched at 7/8 or 8/8 HLA-A, B, C, or DRβ1 loci by molecular typing

- If match is not at allele level, suitability for donation requires discussion with
and approval by the principal investigator

- Not an identical twin

PATIENT CHARACTERISTICS:

- Karnofsky performance status 60-100%

- Creatinine clearance ≥ 55 mL/min

- Total bilirubin ≤ 2 times upper limit of normal (ULN) (unless due to Gilbert's
disease or malignancy)

- ALT and AST ≤ 4 times ULN

- DLCO ≥ 40%

- FEV1/FVC ratio ≥ 50% of predicted

- Cardiac ejection fraction ≥ 40%

- Not pregnant or nursing

- Fertile patients must use effective contraception

- Not receiving supplementary continuous oxygen

- No NYHA grade II-IV cardiac disease

- HIV negative

- No evidence of active hepatitis B (i.e., positive HBsAg and/or positive HBeAg or high
copy number on quantitative RNA testing) or hepatitis C

- No active uncontrolled infection or immediate life-threatening condition

- No uncontrolled medical illnesses (e.g., uncontrolled systemic hypertension or
diabetes)

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- Prior cytoreductive chemotherapy or irradiation to areas of bulky disease allowed, as
determined by the primary physician in consultation with the study investigators

- No other concurrent anti-tumor therapy