BM-CD34⁺ cells do not contain the t(14; 18) translocation. CD34⁺ cells were enriched to high purity using an immunomagnetic technique, followed by FACS sorting for CD34 and CD19 expression. The DNA extracted from the different subpopulations was amplified by a sensitive PCR method for the detection of bcl-2/IgH rearrangement. The PCR results from one representative patient (K.A.) are shown. (M), 100 bp DNA-ladder; (−), negative control; (+), patient-specific positive control; (MNC), mononuclear cells; (*), primer-dimers.