Inclusion Criteria:

- Patients must have a confirmed initial diagnosis of mantle cell non-Hodgkin's
lymphoma by histology according to the WHO classification .

- Patients must have Ann Arbor bulky stage II, stage III, or stage IV disease at
diagnosis. Bulky stage II disease is defined as a mediastinal mass greater than
one-third of the maximum chest diameter, or any other mass greater than or equal to
10 cm in maximum diameter.

- Patients must have less than an average of 25% of the intratrabecular marrow space
involved by NHL in bilateral bone marrow biopsy specimens as assessed microscopically
at study entry. A unilateral bone marrow biopsy demonstrating <10% involvement with
NHL is also adequate.

- Patients must have evidence that their tumor tissue expresses the CD20 antigen.
Immunoperoxidase stains of paraffin-embedded tissue showing positive reactivity with
L26 antibody or immunoperoxidase stains of frozen tissue showing positive reactivity
with Anti-B1 Antibody (Coulter Clone) or similar commercially available CD20 antibody
or evidence of CD20 positivity by flow cytometry are acceptable evidence of CD20
positivity. This must be performed within 42 days of study entry.

- Patients must have a performance status of at least 60% on the Karnofsky Performance
Scale and an anticipated survival of at least 3 months.

- Patients must have an ANC greater than or equal to 1500 cells/mm3 and a platelet
count greater than or equal to 100,000 cells/mm3 within 14 days of study enrollment.
These blood counts must be sustained without support of hematopoietic cytokines or
transfusion of blood products.

- Patients must have adequate renal function (defined as serum creatinine <1.5 times
the upper limit of normal) and hepatic function (defined as total bilirubin <1.5
times the upper limit of normal and AST <5 times the upper limit of normal) within 14
days of study enrollment.

- Patients must have bi-dimensionally measurable disease. At least one lesion must be
greater than or equal to 2.0 x 2.0 cm by computerized tomography scan.

- Females of childbearing potential must have a negative serum pregnancy test within 7
days prior to study enrollment.

- Patients must have a cardiac left ventricular ejection fraction of greater than or
equal to 50% by ventriculography or echocardiogram.

Exclusion Criteria:

- Patients who have received prior chemotherapy, biologic therapy, steroids, or
radiation therapy as treatment for their MCL

- Patients with active obstructive hydronephrosis

- Patients with serious illness that would preclude evaluation

- Patients with prior malignancy other than lymphoma, except for adequately treated
skin cancer, in situ cervical cancer, or other cancer for which the patient has been
disease free for 5 years

- Patients with known HIV infection

- Patients who are HAMA positive

- Patients with known brain or leptomeningeal metastases.

- Patients who are pregnant or breastfeeding. Males and females must agree to use a
contraceptive method while on study and for 6 months after receiving Iodine-131
Anti-B1 Antibody.

- Patients with active infection requiring IV anti-infectives at the time of study
enrollment.