Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed B-cell non-Hodgkin's lymphoma (NHL)

- Any grade allowed

- CD20-positive disease

- Measurable disease, defined as ≥ 1 bidimensionally measurable lesion > 1.5 cm by CT
scan

- Failed ≥ 1 prior standard chemotherapy regimen OR rituximab therapy for NHL

PATIENT CHARACTERISTICS:

Age

- Over 18

Performance status

- ECOG 0-1 OR

- Karnofsky 80-100%

Life expectancy

- At least 6 months

Hematopoietic

- Hemoglobin > 10 g/dL*

- Absolute neutrophil count > 1,500/mm^3*

- Platelet count > 100,000/mm^3* NOTE: *Transfusion independent

Hepatic

- Bilirubin < 1.5 times upper limit of normal (ULN)

- AST and ALT < 2.5 times ULN

Renal

- Creatinine < 1.5 times ULN

Other

- Not pregnant or nursing

- Negative pregnancy test

PRIOR CONCURRENT THERAPY:

Biologic therapy

- See Disease Characteristics

- At least 12 months since prior rituximab

Chemotherapy

- See Disease Characteristics

- At least 4 weeks since prior investigational or conventional chemotherapy and
recovered

Endocrine therapy

- Not specified

Radiotherapy

- Recovered from prior investigational or conventional radiotherapy

- At least 4 weeks since prior radiotherapy to the index lesion

Surgery

- Recovered from prior investigational or conventional surgery