Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically proven relapsed or refractory, low grade or
transformed low grade B-cell non-Hodgkin's lymphoma including the following: Small
lymphocytic Follicular small cleaved cell Follicular mixed small cleaved and large cell
(less than 50% large cell component) Tumor must be positive for CD20 antigen Relapse or
disease progression following at least 1 chemotherapy regimen or failure to achieve an
objective response (complete or partial response) on prior chemotherapy regimen No disease
progression, within 1 year of irradiation, arising in a field previously irradiated with
more than 3500 cGy Mean of no greater than 25% intratrabecular marrow space involved with
lymphoma on bilateral iliac crest bone marrow biopsy 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: 19 and over Performance status: Karnofsky 60-100% Life
expectancy: At least 3 months Hematopoietic: Absolute neutrophil count at least 1,500/mm3
Platelet count at least 100,000/mm3 Hepatic: Bilirubin less than 1.5 times upper limit of
normal (ULN) AST less than 5 times ULN Renal: Creatinine less than 1.5 times ULN No active
obstructive hydronephrosis Cardiovascular: No New York Heart Association class III or IV
heart disease Other: No active infection requiring IV antibiotics No other concurrent
illness that would preclude evaluation No prior malignancy within the past 5 years except
adequately treated skin cancer, carcinoma in situ of the cervix, or lymphoma HIV negative
Not pregnant or nursing Negative pregnancy test Fertile patients must use effective
contraception during and for 6 months after study No prior allergic reaction to iodine
other than IV iodine containing contrast materials Human antimouse antibody negative

PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior immunotherapy or
cytokine treatment and recovered No prior hematologic stem cell transplantation
Chemotherapy: See Disease Characteristics At least 4 weeks since prior chemotherapy (at
least 6 weeks since prior nitrosoureas) and recovered Endocrine therapy: Not specified
Radiotherapy: See Disease Characteristics At least 4 weeks since prior radiotherapy and
recovered No prior radioimmunotherapy Surgery: Not specified Other: No concurrent IV
antibiotics