Quantitative flow cytometry can distinguish between normal and leukaemic B-cell precursors

Area of Science:

• Immunology
• Hematology
• Oncology

Background:

• Minimal residual disease (MRD) detection in B-lineage acute lymphoblastic leukemia (ALL) is challenging due to shared antigens (TdT, CD10, CD19) between malignant and normal cells.
• Standard immunological detection methods can lead to misinterpretation of regenerating B-cells as signs of relapse.

Purpose of the Study:

• To develop a quantitative method for distinguishing between normal B-cell precursors and minimal residual ALL blasts.
• To establish reliable criteria for MRD detection in B-lineage ALL using antigen expression levels.

Main Methods:

• Quantitative double-labelling flow cytometry was employed to measure the number of antigen molecules per cell.
• Expression levels of TdT, CD10, and CD19 were quantified in normal B-cell precursors and B-lineage ALL blasts.
• Analysis included healthy donors, regenerating marrows, and ALL patient samples.

Main Results:

• Significant differences in TdT, CD10, and CD19 expression levels were observed between normal precursors and ALL blasts.
• Normal TdT+ precursors exhibit higher TdT and lower CD10/CD19 than ALL blasts.
• Regenerating marrows showed an increased percentage of B-cell precursors, primarily of the TdT-/CD10+/CD19+ type.

Conclusions:

• Quantitative analysis of TdT, CD10, and CD19 provides a clear distinction between normal B-cell precursors and minimal residual ALL.
• This approach helps avoid misdiagnosis of relapse due to regenerating B-cells in ALL patients.
• Accurate MRD detection is crucial for effective B-lineage ALL management.