PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics At least 6 weeks since prior rituximab At least 3 weeks since prior immunotherapy and recovered No prior radioimmunotherapy At least 2 weeks since prior filgrastim (G-CSF) or sargramostim (GM-CSF) Chemotherapy: See Disease Characteristics At least 3 weeks since prior chemotherapy (6 weeks for nitrosourea or mitomycin) and recovered Endocrine therapy: Not specified Radiotherapy: See Biologic therapy At least 3 weeks since prior radiotherapy and recovered No prior external beam radiotherapy to more than 25% of active bone marrow (involved field or regional) Surgery: At least 4 weeks since prior major surgery (other than diagnostic) and recovered Other: At least 3 weeks since prior anticancer therapy and recovered At least 8 weeks since prior phase II drugs and recovered No other concurrent myelosuppressive antineoplastic agents No other concurrent antineoplastic therapy