Inclusion Criteria

DISEASE CHARACTERISTICS: Acute leukemias in the following categories: Histologically
documented ANLL in first remission (CR1) or second remission (CR2) Pediatric ANLL patients
in CR1 eligible provided they are not enrolled on protocol CCG-2891 ALL in CR1 presenting
with at least 1 of the following high-risk features: WBC at presentation greater than
50,000/mm3 (200,000/mm3 in pediatric patients) Hypoploidy as measured by flow cytometry
Pseudodiploidy with translocations t(9;22), t(4;11), and t(8;14) CR not achieved until
after 4 weeks of induction therapy ALL in CR2 that has relapsed in the bone marrow
following a first remission regardless of time of relapse Acute biphenotypic leukemia
(mixed myeloid and lymphoid lineage at presentation) in CR1 or CR2, i.e., patients
classified as lymphoblastic or myeloblastic based on FAB morphology and histochemistry
features Adult acute undifferentiated leukemia (no evidence of lymphoid or myeloid
differentiation) and in CR1 or CR2 Patients in this category are analyzed separately CR
defined as no evidence of leukemia at time of transplantation as documented by
normocellular bone marrow aspirate containing no more than 5% blasts no more than 2 weeks
prior to cytoreduction Normal diagnostic LP or Ommaya reservoir tap required no more than
2 weeks prior to start of cytoreduction in all ALL patients and in ANLL patients at risk
for CNS disease No extramedullary disease at time of transplantation HLA-identical,
MLC-compatible related donor required Donor must be healthy and willing to undergo general
anesthesia and donation procedure For T-cell depletion, donor should be able to have a
volume of 15 ml/kg patient body weight harvested safely

PATIENT CHARACTERISTICS: Age: Any age (5 to 55 to be eligible for randomization)
Performance status: Karnofsky (or Lansky) 70-100% Life expectancy: Greater than 8 weeks
Hematopoietic: See Disease Characteristics Hepatic: Bilirubin less than 1.5 mg/dl SGOT no
greater than 3 times upper limit of normal (ULN) (both parameters stable for at least 4
weeks prior to transplantation) Renal: Creatinine less than 2 times ULN and stable for at
least 4 weeks prior to transplantation OR Creatinine clearance at least 70 mL/min
Cardiovascular: Fractional shortening greater than 28% on echocardiogram (23-28% if FS
increases as a response to stress on supine bicycle ergometer) LVEF at least 50% on
echocardiogram or MUGA Other: In good clinical condition at time of transplantation with
no medical problems that would significantly increase the risk of the procedure No
infection at time of transplantation Not pregnant or nursing

PRIOR CONCURRENT THERAPY: See Disease Characteristics