Inclusion Criteria:

- Less than or equal to 18 years of age (may be greater than 18 years of age if
currently a St. Jude patient).

- Patients with relapsed or refractory AML, T-ALL/T-LL, CML, JMML, MDS, ESFT or RMS who
are not eligible for SCT and have persistent disease after remission induction(s)
therapy as evidenced by bone marrow morphology, cytogenetics, flow cytometry,
molecular pathology, and/or restaging scans.

- At least two weeks since receipt of any biological therapy, systemic chemotherapy,
and/or radiation therapy.

- Shortening fraction greater than or equal to 25%.

- Glomerular filtration rate greater than or equal to 50 cc/min/1.73 m2.

- Pulse oximetry greater than or equal to 92% on room air.

- Direct bilirubin less than or equal to 3.0 mg/dL.

- Karnofsky or Lansky performance score of greater than or equal to 50.

- No known allergy to murine products or HAMA testing results within normal limits.

- Does not have a current pleural or pericardial effusion.

- Has a suitable adult family member donor available for NK cell donation.

- Is not receiving more than the equivalent of prednisone 10 mg daily.

- Not pregnant (negative serum or urine pregnancy test to be conducted within 7 days
prior to enrollment).

- Not lactating.

Eligibility criteria prior to initiation of protocol therapy (preparative regimen)

- Alanine aminotransferase (ALT) is no more than 2 times the upper limit of normal.

- Aspartate transaminase (AST) is no more than 2 times the upper limit of normal.

- Has recovered from all acute NCI Common Toxicity Criteria grade II-IV non-hematologic
acute toxicities resulting from prior therapy per the judgment of the PI

Eligibility criteria (NK cell DONOR):

- Family member with a greater than or equal to 3 of 6 HLA match to recipient.

- At least 18 years of age.

- HIV negative.

- Not pregnant (negative serum or urine pregnancy test to be conducted within 7 days
prior to enrollment). Not lactating.