Comparison between TaqMan and LightCycler technologies for quantification of minimal residual disease by using immunoglobulin and T-cell receptor genes consensus probes.

Quantification of residual leukemic cells at early time points during therapy can reliably predict the outcome in children with acute lymphoblastic leukemia (ALL). Recently, semiquantitative minimal residual disease (MRD) detection assays such as dot-blot hybridization have been replaced by real-time quantitative PCR. We tested the flexibility of the two most used real-time PCR machines: the SDS 7700 or 'TaqMan' (TM) (Applied Biosystems) and the LightCycler (LC) (Roche) instruments. Clonal T-cell receptor and immunoglobulin gene rearrangements were used for MRD detection with germline hydrolyzation probes and clone-specific primers. Sensitivity tests for 65 clonal gene rearrangements and MRD quantification in 90 bone marrow samples during therapy of 49 children with ALL at diagnosis or relapse were performed with both machines. Both real-time PCR systems provided specific results for MRD quantification in all follow-up samples. In conclusion, we were able to demonstrate that TM and LC real-time PCR technologies produce similar MRD quantification results and that the quantification assays can be easily transferred from one detection system to the other. Using the same detection format, both techniques can be applied in combination in multicenter MRD studies.