The protocol treatment is to evaluate clinical effects of donor-derived natural killer cells that are given after HLA-mismatched hematopoietic cell transplantation.

Those patients with acute leukemia, which is not responding to coventional chemotherapy, will be treated. The clinical effects will be evaulated in terms of safety (side effects) and anti-leukemia effect.

Inclusion Criteria:

Patients with acute leukemia, which are refractory to standard treatment. Patients should be 17 years of age or older. The performance status of the patients should be 70 or over by Karnofsky scale. Patients should not have excessive hepatic dysfunction (bilirubin less than 3.0 mg/dl, AST less than 5 times the upper normal limit).

Patients should not have excessive renal dysfunction (creatinine less than 3.0 mg/dl).

Patients should not have clinically-evident cardiac or pulmonary dysfunction. Patients and donors must sign informed consent.

Exclusion Criteria:

Patients who are pregnant or lactating are not eligible.