Immunotoxin Therapy in Treating Patients With Hairy Cell Leukemia

DISEASE CHARACTERISTICS: * Histologically confirmed refractory or recurrent hairy cell leukemia * Relapsed after less than 2 years of complete remission after purine analog therapy * Must have at least one of the following indications for therapy: * Progressive or massive splenomegaly * Cytopenia defined by the following: * Absolute neutrophil count less than 1,000/mm\^3 OR * Platelet count less than 100,000/mm\^3 OR * Hemoglobin less than 12 g/dL * More than 20,000 hairy cells/mm\^3 * Symptomatic adenopathy * Constitutional symptoms including tumor-related fever or bone pain * Evidence of CD22 positivity by 1 of the following: * More than 15% of malignant cells from a site must react with anti-CD22 by immunohistochemistry * More than 30% of malignant cells from a site CD22+ by fluorescent-activated cell sorter * More than 400 CD22 sites/cell (average) on malignant cells as assessed by radiolabeled anti-CD22 binding * No CNS disease requiring treatment * No patients whose serum neutralizes BL22 immunotoxin in tissue culture, due to either antitoxin or antimouse-IgG antibodies * No patients whose serum neutralizes more than 75% of the activity of 1 microgram/mL of BL22 immunotoxin PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * Karnofsky 60-100% Life expectancy: * More than 6 months Hematopoietic: * See Disease Characteristics * Pancytopenia due to disease allowed Hepatic: * ALT and AST less than 2.5 times upper limit of normal (ULN) * Bilirubin less than 1.5 times ULN Renal: * Creatinine no greater than 2.0 mg/dL Pulmonary: * FEV1 at least 60% of predicted * DLCO at least 55% of predicted Other: * HIV negative * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: * Prior bone marrow transplantation allowed * At least 3 weeks since prior interferon for the malignancy * More than 3 months since prior monoclonal antibody therapy (e.g., rituximab) Chemotherapy: * See Disease Characteristics * At least 3 weeks since prior cytotoxic chemotherapy for the malignancy Endocrine therapy: * Not specified Radiotherapy: * At least 3 weeks since prior whole body electron beam radiotherapy for the malignancy * Radiotherapy within the past 3 weeks allowed provided less than 10% of total bone marrow was treated and patient has measurable disease outside the radiation port Surgery: * Not specified Other: * At least 3 weeks since prior retinoids for the malignancy * At least 3 weeks since any other prior systemic therapy for the malignancy * No concurrent therapeutic warfarin