Detection of MRD in bone marrow samples. Results of PCR analysis for the 20 patients in whom a probe for IgH (9 patients) or a bcl-1/IgH rearrangement (11 patients) was available. The analysis was carried out on bone marrow samples obtained at diagnosis, after standard-dose chemotherapy, after cyclophosphamide, after cytarabine, after the second autografting (day 0), and at the indicated follow-up times. • indicates PCR-positive; ○, PCR-negative. UPN indicates unique patient number.