EuroFlow-based multidimensional analysis of normal and malignant BCP cells. (A) (Left) Automated population separation of normal B-cell differentiation in BM (BCP cells and more mature B cells). (Center) Automated population separation view of BCP cells in regenerating BM (blue dots), plotted against the normal B-cell differentiation (green arrow), showing that regenerating BCP cells (hematogones) are fully comparable to BCP cells in normal BM. (Right) Plotting of ALL cells (red dots) against normal B-cell differentiation (green), showing that the ALL cells differ from normal B cells. (B) (Left) ALL cells (in red) plotted against normal BCP cells (green). (Center) ALL cells (red) plotted against immature CD34⁺ BCP cells only, showing that the ALL cells separate from their normal counterparts. (Right) The separation is not based on a single marker but on multiple markers (in this case: CD10, FSC, CD38, etc). (C) Normalized B-cell maturation pathway (gray zone), allowing to assess differences in CD38 expression between ALL cells and normal cells to support MRD detection. (Left) MRD analysis in BM at day 33, showing complete deletion of the normal BCP cells, but presence of normal more mature B cells (green) within the normal B-cell pathway, as well as a small population of ALL cells with aberrant (low) CD38 expression. (Right) MRD analysis of BM at day 78 of the same patient as in the left panel, now showing regeneration of normal BCP cells (blue dots), which fit with the normalized B-cell differentiation pathway (gray zone). No aberrant cells were detected at day 78 in this patient sample.