Safety Study of NHL With 90Y-hLL2 IgG

Inclusion Criteria: * All patients must have a histologic or cytological diagnosis of B-cell lymphoma, and have failed at least one regimen of standard chemotherapy. All histologic grades of non-Hodgkin's lymphoma (NHL) will be eligible for these studies. * Patients must be \> 18 years of age * Measurable disease by CT, with at least one lesion \> 1.5 cm in one or both dimensions * less than 25% bone marrow involvement as determined by bone marrow biopsy * Patient must have greater than 15% cellularity of the bone marrow. * Patients must be at least 4 weeks beyond any major surgery. * Patients must be at least 4 weeks beyond any radiation therapy to the index lesion and must have recovered from radiation induced toxicity. * Patients must be at least 4 weeks beyond prior chemotherapy and/or immunotherapy, or 2-weeks after corticosteroids, and their blood counts must be within the eligibility criteria. Corticosteroids may, however, be given concomitantly if used to treat adrenal insufficiency * Patients must have a performance status of 70 or greater on the Karnofsky scale equivalent to ECOG 0-1 (See Appendix A) and a minimal life expectancy of 6 months. * Patients must be able to give cognizant informed consent. Exclusion Criteria: * Patients with a significant concurrent medical complication including severe anorexia, nausea or vomiting that in the judgement of the Investigator could affect the patient's ability to tolerate or complete this study. * Patients with metastasis to the brain. * Patients with extensive irradiation to more than 25% of their red marrow will be excluded, except those who had total body irradiation in the context of bone marrow or stem cell transplantation regimen with subsequent engraftment of a functional marrow (i.e., resulting in normal peripheral blood counts). Subjects who have received external radiation to specific organs or areas at the maximum tolerated level are also excluded. * Women who test positive for pregnancy. * Patients with splenomegaly. * Patients with \> 4 treatment regimens prior to this protocol, including chemotherapy, radiotherapy and/or other immunotherapy. * Patients with prior radioimmunotherapy treatments (unless for retreatment under this protocol). * Patients receiving rituximab within 3 months, unless progressing after treatment. * Patients with \<50% LVEF by required MUGA or 2-D ECHO. * Patients with \<60% of predicted value by required pulmonary function tests. * Patients who have active Hepatitis B or C or are known HIV positive. * Patients with another primary malignancy (except basal/squamous cell carcinoma of the skin or carcinoma in-situ of the cervix. * Patients with other serious medical, surgical, or psychiatric history, unless currently stable and well controlled, without significant increase in treatment medications for at least 30 days preceding study entry.