Inclusion Criteria

DISEASE CHARACTERISTICS:

- Diagnosis of intermediate- or high-grade non-Hodgkin's lymphoma according to the
Working Formulation, including the following subtypes:

- Diffuse large cell lymphoma

- Diffuse mixed cell lymphoma

- Immunoblastic large cell lymphoma

- CD20+ disease

- Measurable progressive or refractory disease

- No primary CNS lymphoma or lymphomatous meningitis NOTE: A new classification scheme
for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of
"indolent" or "aggressive" lymphoma will replace the former terminology of "low",
"intermediate", or "high" grade lymphoma. However, this protocol uses the former
terminology.

PATIENT CHARACTERISTICS:

Age

- 18 and over

Performance status

- ECOG 0-2

Life expectancy

- Not specified

Hematopoietic

- Lymphocyte count less than 20,000/mm^3

- Absolute neutrophil count at least 1,000/mm^3

- Platelet count at least 75,000/mm^3

- Hemoglobin at least 9.5 g/dL

Hepatic

- SGOT and SGPT no greater than 1.5 times upper limit of normal

- Bilirubin normal

- No liver disease

- Hepatitis C-seropositive patients are allowed provided they have no active disease,
as demonstrated by any of the following:

- Undetectable hepatitis C viral loads

- Biopsy showing no active disease

- Normal transaminases on at least 3 different occasions within the past year

Renal

- Creatinine normal

Cardiovascular

- No clinically significant cardiac dysfunction

- No myocardial infarction within the past 6 months

- No heart failure within the past 6 months

Pulmonary

- No clinically significant pulmonary dysfunction

- Patients with prior radiotherapy to the lung or autologous transplantation must have
FEV greater than 50% and DLCO greater than 50% within 8 weeks before study treatment

Other

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- HIV negative

- No significant infections within the past 2 weeks (including pneumonia or bronchitis)

- No history of autoimmune disease

- No prior or concurrent malignancy except inactive nonmelanoma skin cancer, carcinoma
in situ of the cervix, or other solid tumor curatively treated with no evidence of
recurrence within the past 2 years

- No symptomatic thyroid disease requiring medical intervention other than replacement
treatment for hypothyroidism

- No prior type 1 hypersensitivity or anaphylactic reactions to murine products,
rituximab, or radioimmunoconjugated anti-CD20 antibody infusion

PRIOR CONCURRENT THERAPY:

Biologic therapy

- At least 3 months since prior autologous bone marrow transplantation

- No prior allogeneic bone marrow transplantation

- No prior interleukin-2

- No prior interferon (alfa, beta, or gamma)

- No concurrent basiliximab, daclizumab, or monoclonal antibody OKT3

Chemotherapy

- More than 30 days since prior chemotherapy

- No concurrent anticancer chemotherapy

Endocrine therapy

- More than 2 weeks since prior systemic steroids

- No concurrent systemic corticosteroids

Radiotherapy

- More than 30 days since prior radiotherapy

- No concurrent radiotherapy

Surgery

- More than 30 days since prior major surgery

Other

- More than 30 days since other prior investigational drugs

- More than 30 days since prior immunosuppressive medications

- No concurrent immunosuppressive medications including the following:

- Cyclosporine

- Mycophenolate mofetil

- Tacrolimus

- Sirolimus