Subjects with BMFS at high risk for graft rejection will undergo allogeneic stem cell transplantation from an HLA identical sibling or match unrelated donor using the identical conditioning regimen utilized in protocol 99-H-0050. Using the Miltenyi CliniMACs system, recipients will receive an allograft on day 0 containing donor CD34+ cells that have been positively selected and T-cell depleted following G-CSF mobilization (goal CD34+ cell dose of 5 times 10(6) CD34+ cells /kg recipient) combined with 2 times 10(7) cells/kg of non-mobilized CD3+ T-cells previously collected and cryopreserved from the same donor by apheresis prior to G-CSF mobilization.