Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed CD20+ B-cell non-Hodgkin's lymphoma (NHL)

- CD20 positive by immunohistochemistry or flow cytometry

- Relapsed or refractory disease

- Bidimensionally measurable disease

- Sole site of measurable disease within a previously irradiated field allowed
provided there was disease progression at that site

- No pre-existing ascites or pleural effusions

- No known CNS involvement by NHL

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Performance status:

- ECOG 0-2

Life expectancy:

- More than 3 months

Hematopoietic:

- Neutrophil count at least 1,000/mm3

- Platelet count at least 50,000/mm3

Hepatic:

- Bilirubin less than 2 mg/dL

- Transaminase less than 2 times upper limit of normal

- No hepatitis B or C

Renal:

- Creatinine less than 2 mg/dL

Cardiovascular:

- No significant cardiovascular disease

- No New York Heart Association class III congestive heart failure

- No myocardial infarction within the past 6 months

- No unstable angina

- No uncontrolled atrial or ventricular cardiac arrhythmias

Pulmonary:

- No concurrent significant pulmonary disease

Other:

- HIV negative

- No acute infection requiring antibiotics

- No fever over 38.2 degrees C within the past 3 days

- No other malignancy within the past 5 years except basal cell or noninvasive squamous
cell skin cancer or carcinoma in situ of the cervix

- No pre-existing autoimmune disease or antibody-mediated disease, including:

- Systemic lupus erythematosus

- Rheumatoid arthritis

- Multiple sclerosis

- Sjogren's syndrome

- Autoimmune thrombocytopenia

- Controlled thyroid disease allowed

- Concurrent autoantibodies without clinical autoimmune disease allowed

- No history of allergic reactions attributed to compounds of similar composition to
study drugs

- No other medical history, including laboratory results, that would preclude study

- No suspected or confirmed poor compliance or mental instability that would preclude
study

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- No prior allogeneic transplantation

- More than 30 days since prior hematopoietic growth factors (e.g., filgrastim (G-CSF)
or epoetin alfa)

- More than 30 days since prior immunotherapy

- More than 90 days since prior monoclonal antibodies as monotherapy for patients who
were unresponsive to treatment (30 days for patients who responded to treatment and
subsequently relapsed)

- No other concurrent biological agents

- No concurrent hematopoietic growth factors (e.g., G-CSF or epoetin alfa)

Chemotherapy:

- More than 30 days since prior chemotherapy

- No concurrent chemotherapy

Endocrine therapy:

- More than 30 days since prior systemic corticosteroids

- No concurrent systemic corticosteroids

Radiotherapy:

- See Disease Characteristics

- More than 30 days since prior radiotherapy

- No concurrent radiotherapy

Surgery:

- Not specified

Other:

- Recovered from prior therapy

- At least 6 months since prior coronary angioplasty

- More than 30 days since prior immunosuppressants

- More than 30 days since prior participation in an investigational drug study

- No concurrent immunosuppressants

- No concurrent anticoagulants except aspirin at doses no greater than 325 mg/day

- No other concurrent anticancer therapy

- No other concurrent investigational agents