Optimizing MRD Identification in B-ALL Using CD123 as a Discriminator of Hematogones and B -Lymphoblasts

Minimal Residual Disease (MRD) refers to the small number of cancer cells that may remain in the body after treatment, serving as a key indicator of relapse risk and guiding treatment decisions. Detecting MRD using flow cytometry can be challenging because normal B-cell precursors (hematogones) and cancerous B-lymphoblasts share similar physical and biological traits, making them hard to distinguish. This study investigated whether the CD123 marker could improve MRD detection and better differentiate hematogones from B-lymphoblasts in B-acute lymphoblastic leukemia (B-ALL). We used a single-tube flow cytometry approach with anti-human monoclonal antibodies targeting CD19, CD20, CD10, CD34, CD123, and CD45. Our findings showed that CD123 significantly improved the ability to distinguish hematogones from residual B-lymphoblasts. CD123 was strongly expressed on residual B-ALL cells, indicated by a high mean fluorescence intensity (MFI), while it showed moderate expression on mature hematogones, and no expression on less mature hematogones or mature B cells. These results demonstrate clearly that analyzing CD123 expression enhances the accuracy of MRD detection in B-ALL patients.