Inclusion Criteria:

• Age less than 65 years. There is no lower age limit. Patients 65 years and older will be accrued on a case-by-case basis to this protocol, after discussion and approval by the principal investigator. The acceptance to this protocol for such patients would be based on the absence of coexisting medical problems, which would seriously compromise the patient's ability to tolerate the known morbidity and risks of bone marrow transplantation.
• Patients must have a 5/6 or 6/6 HLA matched, unrelated donor of bone marrow stem cells.
• Each patient must be willing to participate as a research subject and must sign an informed consent form after having been advised as to the nature and risk of the study prior to entering the protocol. Parents or legal guardians of patients who are minors will sign the informed consent form after being advised of the nature and risks of the study. Attending physicians in the Bone Marrow Transplant Service will enroll patients to this study and will obtain written consents.

Eligibility Criteria - Donor

• 5/6 or 6/6 HLA matched with the recipient as determined by molecular testing. Donors will be identified through the National Marrow Donor Program for unrelated donors.
• Donor selection will be performed as outlined in the donor selection SOP's. In patients who have more than one potential donor preference will be given to donors who have no evidence of CMV exposure (if the recipient is CMV-), those who are younger and those who are male. Selection of an unrelated donor from the NMDP registry will proceed according to the donor selection SOP. Molecular testing of HLA-A, B, and DR alleles will identify potential donors and the American Red Cross HLA lab will confirm all typing. Donor selection will be coordinated with transplant physician and the HLA laboratory director. Preference will be given to donors who are 6/6 molecular matches, those who are CMV- (if the recipient is CMV-), those who are younger, and males.

Exclusion Criteria:

• Active CNS leukemia involvement.
• Female patients who are pregnant or breast feeding
• Karnofsky performance status < 70%, (appendix 1).
• Left ventricular ejection fraction of < 40%.
• Serum creatinine > 1.5 X normal
• Patients seropositive for HIV; HTLV -1, or with evidence of chronic active hepatitis as demonstrated by detection of hepatitis surface antigen in the serum
• Patients with serologic evidence of hepatitis B or C exposure will undergo liver biopsy to assess for presence of active hepatitis or fibrosis and quantification of risk of proceeding with transplant
• Patients not providing informed consent.
• Patients with known hypersensitivity to E. Coli derived products.
• SGOT and SGPT > 2.5 x ULN, unless thought to be disease related
• Total bilirubin > 2.0 mg/dl, with direct bilirubin > 0.5 mg/dl