Inclusion Criteria

DISEASE CHARACTERISTICS:

- Biopsy proven diagnosis of low- or intermediate-grade* non-Hodgkin lymphoma (NHL)
including any of the following:

- Follicular small cleaved

- Follicular mixed

- Follicular large cell

- Diffuse small cleaved

- Diffuse mixed

- Diffuse large cell

- Immunoblastic (working formulation B, C, D, E, F, G and H) NOTE: *A new
classification scheme for adult non-Hodgkin 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.

- Mantle cell and transformed low-grade lymphomas allowed

- Demonstrated monoclonal CD20-positive B-cell population in lymph nodes and/or bone
marrow

- Favorable biodistribution on imaging dose

- Patient either relapsed after achieving a complete (CR) or partial response (PR) to
prior therapy, never responded to prior therapy, or has poor-risk disease

- Sensitivity of disease based on 1 of the following:

- Induction failure: patients who did not achieve a CR or PR from induction
chemotherapy

- Resistant relapse: patients who did not achieve a CR or PR from the most
recent standard salvage chemotherapy

- Sensitive relapse: patients who did achieve a CR or PR from the most recent
standard salvage chemotherapy

- Poor-risk disease defined as any of the following:

- Age-adjusted International Prognostic Index (IPI) High- (3 risk factors) or
High-Intermediate (2 risk factors) based on the following risk factors:

- Stage III-IV disease

- Elevated serum lactate dehydrogenase level

- ECOG performance status 2-4

- Patients with aggressive NHL including mantle cell lymphoma and who
required 2 different induction chemotherapy regimens to achieve a CR/PR

- Patients with B-cell NHL and who failed to achieve a CR after adequate
induction chemotherapy regimen(s)

- Patients must have bone marrow aspiration and biopsy within 42 days before salvage
chemotherapy or stem cell collection which show ≤ 10% lymphomatous involvement of
total cellularity

- Normal cytogenetic study on bone marrow (prior to salvage chemotherapy or stem cell
collection)

- Cytogenetic study on peripheral blood is acceptable if bone marrow biopsy has
already been done and shows no sign of myelodysplastic syndrome (MDS) or
lymphoma and a repeat bone marrow is deemed unnecessary by attending physician

- No active or prior history of CNS diseases

- No human anti-mouse antibody (HAMA) or human anti-chimeric antibody

PATIENT CHARACTERISTICS:

- ECOG performance status (PS) 0-1 or Karnofsky PS 80-100%

- Platelet count normal

- Serum creatinine ≤ 1.5 mg/dL or creatinine clearance ≥ 60 mL/min

- FEV_1 > 65% of predicted or DLCO ≥ 50% of predicted

- LVEF > 50% by ECHO or MUGA scan

- Bilirubin ≤ 1.5 times normal

- SGOT or SGPT ≤ 2 times normal

- HIV antibody-negative

- No prior malignancy except for adequately treated basal cell or squamous cell skin
cancer, adequately treated noninvasive carcinoma, or other cancer from which the
patient has been disease-free for at least five years

- No active evidence of hepatitis B or C infection

- No hepatitis B surface antigen positivity

- No history of alcohol abuse

- Body weight ≤ 250 pounds

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- Patients who have received involved field external beam therapy to area excluding
lung, heart, liver and kidney are allowed, but will be evaluated on a case-by-case
basis

- Patients must have recovered from last therapy and should be at least four weeks from
prior radiation or chemotherapy

- No prior radioimmunotherapy

- No prior bone marrow transplantation