Inclusion Criteria:

INCLUSION CRITERIA - RECIPIENT: (all of the following)

- Ages 5-50 years

- Acute myelogenous leukemia (AML) or acute lymphoblastic leukemia (ALL)

- Second remission (CR2) in standard risk patients or CR1 in cases with high-risk
features (poor cytogenetic changes or secondary to myelodysplastic syndrome)

- Unavailability of HLA identical related donor or matched unrelated donor.

- Unavailability of other therapeutic intervention that prolongs patient survival.

- Lack of active infection.

- No history of allergy to CAMPATH.

- For adults: Ability to comprehend the investigational nature of the study and provide
informed consent. For minors: Written informed consent from one parent or guardian..

- Social and intellectual competency of the patient and his/her family to follow
medical recommendations.

INCLUSION CRITERIA - DONOR:

- The donor must be haploidentical with the recipient: In the order of priority,
siblings who have an identical paternal HLA haplotype with the patient, offspring
(for female patients that do not have appropriate sibling), and mother.

- Possibly, it is better that the donor and recipient to be of same blood group and
sex..

- Possibly, it is better that female donors not to be multiparous.

- Weight greater than or equal to 18 kg.

- Age between 2 and 60 years old.

- For adults: Ability to comprehend the investigational nature of the study and provide
informed consent. For minors: Written informed consent from one parent or guardian
and informed assent: The process will be explained to the minor on a level of
complexity appropriate for their age and ability to comprehend.

- Negative two-way WBC crossmatch with the recipient.

Exclusion Criteria:

EXCLUSION CRITERIA - RECIPIENT: (ANY OF THE FOLLOWING)

- Major anticipated illness or organ failure incompatible with survival from
transplantation.

- Severe psychiatric illness. Mental deficiency sufficiently severe as to make
compliance with the transplantation procedure unlikely and making informed consent
impossible.

- Positive pregnancy test for women of childbearing age.

- HIV positive

- Active infection

- Left ventricular ejection fraction less than 40%

- AST/SGOT greater than 20 x ULN (CTCAE grade IV v3.0)

- Bilirubin greater than 10 x ULN (CTCAE grade IV v3.0)

- Creatinine greater than 6 x ULN (CTCAE grade IV v 3.0)

- Occurrence of allergy symptoms and signs during CAMPATH infusion. EXCLUSION CRITERIA
- DONOR: (ANY OF THE FOLLOWING)

- Pregnant or lactating

- Unfit to receive filgrastim (G-CSF) and undergo apheresis (abnormal blood counts,
history of stroke, uncontrolled hypertension)

- Sickling hemoglobinopathies including HbSS, HbAS, HbSC

- HBsAg or HIV positive

- Active infection

- CMV positive (for CMV negative recipients)

- Severe psychiatric illness. Mental deficiency sufficiently severe as to make
compliance with the BMT treatment unlikely and making informed consent impossible

- Contraindication to general anesthesia.