Patients were chosen based on the number of cells available for inoculation into mice. We were only able to obtain sufficient peripheral cells to inject groups of mice for each patient during leukemic phases of disease, which are defined as aggressive disease for the purpose of this study, or after cytokine mobilization (here defined as having minimal disease). PBMC from patients with aggressive disease had from 3% to 20% leukemic plasma cells. The pleural effusion from patient 1 was > 90% plasma cells. G-CSF mobilized aphereses were taken fresh at the time of apheresis, or taken after cryopreservation at the time of reinfusion. The number of comobilizing malignant cells is unknown but for those patients for whom patient-specific sequences had been derived, RT-PCR showed the presence of clonotypic transcripts in purified RNA. Minimal disease was defined as indicated in “Materials and Methods.”