RQ-PCR analysis of Vδ2-Jα rearrangements. (A) Schematic representation of RQ-PCR analysis of Vδ2-(Dδ3)-Jα rearrangements. The positions and sequences of the germline Vδ2 TaqMan probe, germline Vδ2 forward primer, and 4 germline Jα primers are indicated. (B) Real-time amplification plots of the serial dilutions of a precursor-B–ALL DNA containing clonal Vδ2-Jα61 gene rearrangement into DNA of the cell line CEM, known to have 2 deleted TCRD alleles. RQ-PCR analysis was performed using the germline Vδ2 TaqMan probe, the Vδ2 forward primer, and the Jα61 primer. Relatively high levels of Vδ2-Jα61 rearrangements were found in thymus (6 × 10^–3). Such rearrangements were also detectable in normal BM, albeit at low levels (less than 10^–4). (C) Real-time amplification plots of the serial diagnosis DNA dilutions into MNC DNA in precursor-B–ALL. RQ-PCR analysis by use of the TaqMan technique was performed using a Vδ2-Jα56 rearrangement with the junctional region-specific primer approach. The reproducible sensitivity in this case reached 10^–5.