Study of mAb 216 With Chemotherapy for Treatment of Pediatric Relapsed or Refractory B-progenitor Acute Lymphoblastic Leukemia

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