Simplified sensitive method for the detection of B-cell clonality in lymphoid malignancies

Molecular response and monitoring of minimal residual disease (MRD) is becoming an essential part of most protocols for treating leukemia and lymphoma patients. Detection of abnormal clones by PCR analysis of complementarity determining regions (CDRs) in immunoglobulin genes is currently standard practice for diagnosis, but is not widely used to monitor MRD because of the low sensitivity of assays that use consensus primers. Use of specific primers can improve the sensitivity of the assay, but is a cumbersome, expensive, and time-consuming process. We developed a simple and cost-effective approach to detect MRD in B-cell malignancies that is usable in clinical laboratories. The new assay uses ligase chain reaction (LCR) to detect clonality. The sensitivity of the LCR assay is 1 per 500 000 cells, and it can detect all subclones that were present in the pretherapy diagnostic sample.