PRIOR CONCURRENT THERAPY: Biologic therapy: Prior murine monoclonal antibody therapy allowed (if unreactive to yttrium Y 90-labeled humanized anti-CD22 monoclonal antibody LL2 by HPLC or ELISA test) Chemotherapy: At least 4 weeks since prior chemotherapy Endocrine therapy: At least 2 weeks since prior corticosteroids (except for adrenal insufficiency) Radiotherapy: At least 4 weeks since prior radiotherapy to the index lesion No prior extensive radiotherapy to greater than 25% of bone marrow (except total body irradiation as part of bone marrow or stem cell transplantation regimen with engraftment of functional marrow (i.e., producing normal peripheral blood counts) No prior maximum tolerated dose levels of radiotherapy to critical organs (e.g., lung, liver, or kidney) Surgery: At least 4 weeks since prior major surgery Other: No other concurrent investigational agents