Radiolabeled Monoclonal Antibody in Treating Patients With Relapsed or Refractory Non-Hodgkin's Lymphoma

DISEASE CHARACTERISTICS: Histologically confirmed low-grade, follicular, or transformed CD20-positive B-cell non-Hodgkin's lymphoma (NHL) Relapsed after prior chemotherapy OR chemotherapy-resistant disease Failed at least 1 prior chemotherapy regimen CD20-positive B-cell population in lymph nodes or bone marrow for International Working Formulation A (small lymphocytic lymphoma) and transformed NHL Bone marrow involvement with lymphoma less than 25% bilaterally No impaired bone marrow reserve defined as at least 1 of the following criteria: Prior myeloablative therapies with bone marrow transplantation or peripheral blood stem cell rescue Platelet count less than 100,000/mm3 Bone marrow cellularity no greater than 15% Marked reduction in bone marrow precursors of one or more cell lines (e.g., granulocytic, megakaryocytic, or erythroid) Failed prior stem cell collection No CNS lymphoma, chronic lymphocytic lymphoma, or HIV or AIDS-related lymphoma No diffuse small lymphocytic/marginal zone lymphoma with lymphocyte count greater than 5,000/mm^3 No pleural effusion NOTE: A new classification scheme for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol uses the former terminology. PATIENT CHARACTERISTICS: Age: 19 and over Performance status: WHO 0-2 Life expectancy: At least 6 months Hematopoietic: See Disease Characteristics Absolute neutrophil count at least 1,500/mm^3 Platelet count at least 100,000/mm^3 Hematocrit greater than 30% Hemoglobin greater than 9.0 g/dL Hepatic: Bilirubin no greater than 1.5 mg/dL Renal: Creatinine no greater than 1.5 mg/dL Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 6 months after study participation No anti-murine antibody reactivity if prior exposure to murine antibodies or proteins No other primary malignancy No other serious nonmalignant disease or infection that would preclude study participation PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics No prior radioimmunotherapy Prior rituximab allowed if more than 6 months to progression after an objective response At least 6 weeks since prior rituximab At least 3 weeks since prior filgrastim (G-CSF) or sargramostim (GM-CSF) Recovered from prior immunotherapy Chemotherapy: See Disease Characteristics No prior fludarabine At least 3 weeks since prior anticancer chemotherapy (6 weeks for nitrosoureas or mitomycin) and recovered No concurrent chemotherapy Endocrine therapy: At least 3 weeks since prior anticancer endocrine therapy No concurrent high-dose systemic corticosteroids (e.g., 50 mg or more of prednisone as a single dose or 50 mg or less of prednisone for more than 6 doses) Radiotherapy: No prior radiotherapy to more than 25% of active bone marrow (involved field or regional) At least 3 weeks since prior anticancer radiotherapy and recovered Surgery: At least 4 weeks since prior surgery (except diagnostic surgery) and recovered Other: No other concurrent anticancer therapy Concurrent oral anticoagulant therapy allowed if platelet count is at least 30,000/mm3