Inclusion Criteria:

- Patients with advanced AML or ALL defined as beyond first remission, primary
refractory disease, or evolved from myelodysplastic or myeloproliferative syndromes;
or patients with MDS expressed as refractory anemia with excess blasts (RAEB),
refractory cytopenia with multilineage dysplasia (RCMD), RCMD with ringed
sideroblasts (RCMD-RS), or chronic myelomonocytic leukemia (CMML)

- Patients not in remission must have cluster of differentiation (CD)45-expressing
leukemic blasts; patients in remission do not require phenotyping and may have
leukemia previously documented to be CD45 negative (because in remission patients,
virtually all antibody binding is to non-malignant cells which make up >= 95% of
nucleated cells in the marrow)

- Patients should have a circulating blast count of less than 10,000/mm^3 (control with
hydroxyurea or similar agent is allowed)

- Patients must have a creatinine clearance greater than 50/ml per minute by the
following formula (test must be performed within 28 days prior to registration):

- Creatinine clearance (CrCl) = (140-age) (Wt in Kg) x 0.85 (female) OR 1.0 (male)
72 x serum Cr*

- Bilirubin < 2 times the upper limit of normal

- Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) < 2 times the
upper limit of normal

- Karnofsky score >= 70 or Eastern Cooperative Oncology Group (ECOG) =< 2

- Patients must have an expected survival of > 60 days and must be free of active
infection

- Patients must have a related donor who is identical for one HLA haplotype and
mismatched at the HLA-A, -B or class II, DR beta 1 (DRB1) loci of the unshared
haplotype with the exception of single HLA-A, -B or DRB1 mismatches

- DONOR: Related donor who is identical for one HLA haplotype and mismatched at the
HLA-A, -B, or DRB1 loci of the unshared haplotype with the exception of single HLA-A,
-B, or DRB1 mismatches

Exclusion Criteria:

- Circulating antibody against mouse immunoglobulin (HAMA)

- Prior radiation to maximally tolerated levels to any critical normal organ

- Cross-match positive with donor

- Patients may not have symptomatic coronary artery disease and may not be on cardiac
medications for anti-arrhythmic or inotropic effects

- Left ventricular ejection fraction < 35%

- Corrected diffusion capacity of carbon monoxide (DLCO) < 35% and/or receiving
supplemental continuous oxygen

- Liver abnormalities: fulminant liver failure, cirrhosis of the liver with evidence of
portal hypertension, alcoholic hepatitis, esophageal varices, hepatic encephalopathy,
uncorrectable hepatic synthetic dysfunction as evidenced by prolongation of the
prothrombin time, ascites related to portal hypertension, bacterial or fungal liver
abscess, biliary obstruction, chronic viral hepatitis, or symptomatic biliary disease

- Patients who are known seropositive for human immunodeficiency virus (HIV)

- Perceived inability to tolerate diagnostic or therapeutic procedures, particularly
treatment in radiation isolation

- Central nervous system (CNS) involvement with disease refractory to intrathecal
chemotherapy and/or standard cranial-spinal radiotherapy

- Women of childbearing potential who are pregnant (beta-human chorionic gonadotropin
positive [b-HCG+]) or breast feeding

- Fertile men and women unwilling to use contraceptives during and for 12 months
post-transplant

- Inability to understand or give an informed consent