Denileukin Diftitox in Treating Patients With Relapsed or Refractory Non-Hodgkin's Lymphoma

DISEASE CHARACTERISTICS: * Histologically confirmed B-cell non-Hodgkin's lymphoma (NHL) of 1 of the following subtypes: * Diffuse large B-cell lymphoma * Follicular lymphoma (grades 1-3) * Small lymphocytic lymphoma * Transformed B-cell lymphoma * Relapsed or refractory disease * Disease failed to respond to or progressed after ≥ 2 prior treatment regimens (e.g., high-dose therapy \[HDT\] with stem cell transplantation \[SCT\]\*) NOTE: \*Patients who have received HDT with SCT are considered to have diminished bone marrow reserve * Diminished bone marrow reserve AND/OR mild to moderate cytopenia, meeting 1 of the following criteria: * Absolute neutrophil count ≥ 1,000/mm\^3 but \< 1,500/mm\^3 (growth factor independent) * WBC ≥ 2,000/mm\^3 but \< 4,000/mm\^3 (growth factor independent) * Platelet count ≥ 40,000/mm\^3 (25,000/mm\^3 if thrombocytopenia is secondary to marrow involvement by lymphoma) but \< 150,000/mm\^3 (platelet transfusion independent) * At least 1 bidimensionally measurable lymph node or tumor mass ≥ 4 cm PATIENT CHARACTERISTICS: Age * 18 and over Performance status * ECOG 0-2 Life expectancy * At least 16 weeks Hematopoietic * See Disease Characteristics Hepatic * Bilirubin ≤ 1.5 times upper limit of normal (ULN) * AST and ALT ≤ 2 times ULN * Albumin ≥ 3.0 g/dL * No history of veno-occlusive disease of the liver * No chronic hepatitis Renal * Creatinine \< 2 times ULN Cardiovascular * No congestive heart failure * No New York Heart Association class III-IV cardiac disease * No ventricular tachycardia * No fibrillation * No myocardial infarction within the past 12 months Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No known HIV positivity * No active GVHD ≥ grade 2 within the past 6 months * No other serious medical illness or active infection that would preclude study participation * No known hypersensitivity to denileukin diftitox or any of its components (e.g., diphtheria toxin, interleukin-2, or their excipients) * No other malignancy within the past 5 years except successfully treated carcinoma in situ of the cervix or basal cell carcinoma PRIOR CONCURRENT THERAPY: Biologic therapy * See Disease Characteristics * At least 6 months since prior allogeneic SCT * No concurrent immunotherapy Chemotherapy * No concurrent chemotherapy Endocrine therapy * No concurrent anticancer hormonal therapy * No concurrent corticosteroids for the treatment of NHL * Concurrent corticosteroids allowed for the following conditions: * Tapering doses of corticosteroids for resolving graft-versus-host disease (GVHD) * Low-dose maintenance corticosteroids for the treatment of an autoimmune disorder * Corticosteroids as premedication prior to denileukin diftitox administration or as transient treatment for hypersensitivity reactions Radiotherapy * More than 4 weeks since prior and no concurrent radiotherapy * No prior radiotherapy to the only site of evaluable disease unless disease progression has occurred at that site Surgery * Not specified Other * At least 3 weeks since prior antilymphoma therapy * More than 4 weeks since prior and no other concurrent experimental therapy, including approved drugs tested in an investigational setting