DISEASE CHARACTERISTICS:

• Diagnosis of relapsed B-cell non-Hodgkin's lymphoma (NHL) after high-dose chemotherapy and autologous stem cell transplantation

• Less than 25% bone marrow involvement with NHL as evidenced by unilateral or bilateral biopsy within the past 6 weeks

  • Bone marrow biopsy should demonstrate 15-20% of cellular space occupied by normal hematopoiesis

• CD20 antigen expression in tumor tissue within the past year as evidenced by 1 of the following:

  • Immunoperoxidase stains of tissue showing positive reactivity with L26 antibody
  • Flow cytometry studies

• Measurable disease

  • More than 2 cm bidimensionally
• No active CNS lymphoma
• No HIV- or AIDS-related lymphoma

PATIENT CHARACTERISTICS:

Age:

• 19 and over

Performance status:

• WHO 0-2

Life expectancy:

• At least 3 months

Hematopoietic:

• Absolute neutrophil count greater than 1,500/mm^3
• Platelet count greater than 150,000/mm^3
• No transfusion dependency

Hepatic:

• Bilirubin less than 2.0 mg/dL
• SGOT or SGPT no greater than 2.5 times upper limit of normal (unless due to lymphomatous infiltration of the liver)

Renal:

• Creatinine less than 2.0 mg/dL
• No active obstructive hydronephrosis

Other:

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 6 months after study therapy
• HIV negative
• No active infection requiring oral or IV antibiotics
• No human antimurine antibody positivity
• No other major medical problems

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• See Disease Characteristics
• At least 4 weeks since prior growth factors
• At least 4 weeks since prior biologic therapy
• No dependency on hematopoietic growth factors (e.g., epoetin alfa, interleukin-11, filgrastim [G-CSF], or sargramostim [GM-CSF])
• No prior radioimmunotherapy
• No other concurrent biologic therapy of any kind

Chemotherapy:

• See Disease Characteristics
• At least 4 weeks since any prior cytotoxic chemotherapy (6 weeks for nitrosoureas)
• No prior fludarabine
• No concurrent chemotherapy

Endocrine therapy:

• No concurrent steroids except as maintenance for non-cancerous disease

Radiotherapy:

• See Biologic therapy
• At least 4 weeks since prior radiotherapy
• No prior pelvic radiotherapy
• No prior radiotherapy to more than 25% of estimated bone marrow reserve
• No concurrent external beam radiotherapy

Surgery:

• Not specified

Other:

• Recovered from all prior therapy
• At least 4 weeks since prior immunosuppressants
• No other concurrent investigational drugs
• No other concurrent anti-cancer therapy