Inclusion Criteria:

- Patients must be > than 12 months at the time of study entry.

- Patients must have had histologic verification of B-lineage ALL with bone marrow
relapse or refractory disease that is unresponsive to traditional chemotherapy.

- For patients WITHOUT prior allogeneic bone marrow transplant (BMT):

- Second or subsequent bone marrow relapse

- Primary refractory marrow disease

- M3 marrow (> 25% blasts)

- For patients WITH prior allogeneic BMT:

- First or subsequent bone marrow relapse post-BMT

- M3 marrow or M2 (> 5% and < 25% blasts) if cytogenetic or variable number tandem
repeat (VNTR) confirmation

- Confirmation of antibody reactivity

- Patient's leukemic blasts (peripheral blood or marrow) must be documented to bind mAb
216 in vitro (Teng lab).

- Patient's red blood cell (RBC) documented to NOT express fetal "i" antigen and RBC
shown to NOT bind mAb 216 in vitro (Teng lab)

- Patient must not be eligible for therapies of higher priority

- Performance level Karnofsky 50% for patients > 10 years of age and Lansky >= 50 for
patients <= 10 years of age.

- Life expectancy must be at least 8 weeks.

- Patients must have fully recovered from the acute toxic effects of all prior
chemotherapy, immunotherapy, or radiotherapy prior to entering this study:

- Myelosuppressive chemotherapy: must not have been received within 2 weeks of
entry onto this study.

- Biologic: at least 7 days since the completion of therapy with a biologic
agent.

- No hematologic criteria for white blood cell (WBC), hemoglobin (Hgb), or platelets

- Patients with thrombocytopenia should be responsive to platelet transfusions and must
not have uncontrolled bleeding.

- Adequate renal function defined as: a serum creatinine that is less than or equal to
1.5 x normal for age

- Adequate liver function defined as: total bilirubin <= 1.5 x upper limit of normal
(ULN) for age, and SGPT (ALT) <= 5 x upper limit of normal (ULN) for age

- Adequate cardiac function defined as: shortening fraction of >= 27% by
echocardiogram, or ejection fraction of >= 50% by gated radionuclide study.

- All patients and/or their parents or legal guardians must sign a written informed
consent/assent.

- All Institutional Review Board (IRB) and Food and Drug Administration (FDA)
requirements for human studies must be met.

Exclusion Criteria:- Central nervous system (CNS) 3 or refractory CNS leukemia

- Isolated extramedullary relapse

- Uncontrolled infection

- Lack of mAb 216 binding to patient's leukemic blasts in vitro

- Binding of mAb 216 to the"i" antigen on patient's erythrocytes

- Prior treatment with rituximab