Flow cytometric detection of minimal residual disease (MRD) in children with B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) requires immunophenotypic discrimination between residual leukaemic cells and B-cell precursors (BCPs) which regenerate during therapy intervals. In this study, EuroFlow-based 8-colour flow cytometry and innovative analysis tools were used to first characterize the immunophenotypic maturation of normal BCPs in bone marrow (BM) from healthy children, resulting in a continuous multiparametric pathway including transition stages. This pathway was subsequently used as a reference to characterize the immunophenotypic maturation of regenerating BCPs in BM from children treated for BCP-ALL. We identified pre-B-I cells that expressed low or dim CD34 levels, in contrast to the classical CD34(high) pre-B-I cell immunophenotype. These CD34(-dim) pre-B-I cells were relatively abundant in regenerating BM (11-85% within pre-B-I subset), while hardly present in healthy control BM (9-13% within pre-B-I subset; P = 0·0037). Furthermore, we showed that some of the BCP-ALL diagnosis immunophenotypes (23%) overlapped with CD34(-dim) pre-B-I cells. Our results indicate that newly identified CD34(-dim) pre-B-I cells can be mistaken for residual BCP-ALL cells, potentially resulting in false-positive MRD outcomes. Therefore, regenerating BM, in which CD34(-dim) pre-B-I cells are relatively abundant, should be used as reference frame in flow cytometric MRD measurements.
- MeSH
- antigeny CD34 metabolismus MeSH
- buněčná diferenciace fyziologie MeSH
- genová přestavba B-lymfocytů imunologie MeSH
- imunofenotypizace metody MeSH
- kostní dřeň fyziologie MeSH
- lidé MeSH
- mladiství MeSH
- pre-B-buněčná leukemie diagnóza imunologie patofyziologie MeSH
- předškolní dítě MeSH
- prekurzorové B-lymfoidní buňky imunologie patologie fyziologie MeSH
- průtoková cytometrie MeSH
- regenerace MeSH
- reziduální nádor MeSH
- těžké řetězce imunoglobulinů imunologie MeSH
- Check Tag
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- předškolní dítě MeSH
- Publikační typ
- časopisecké články MeSH
The expression of CD27 and CD44 correlate with the genotype of B-precursor acute lymphoblastic leukemia (ALL). Based on the expression of these antigens, we identified counterparts of TEL/AML1(pos) and TEL/AML1(neg) leukemic cells in nonmalignant bone marrow. Although CD27 is known as a marker of mature memory B cells, we recently showed that CD27 is also expressed by malignant and nonmalignant B precursors. Here, we show that CD27 and CD44 delineate stages of B-precursor development. Well-established differentiation markers showed that the developmental sequence starts from undetermined progenitors, expressing CD44. Upon B-lineage commitment, cells gain CD27 and lose CD44. The CD27(pos)CD44(neg) (CD27 single positive, 27SP) cells are the earliest stage within CD10(pos)CD19(pos) B precursors and express RAG-1 and TDT. These cells correspond to TEL/AML1(pos) ALL (1/4 pediatric B-precursor ALL). The development follows to CD27/CD44 double-positive (27/44DP) stage, 44SP stage and CD27/CD44 double-negative (27/44DN) stage. Before exit to periphery, CD44 is reexpressed. The 27/44DP cells are mostly large and profoundly suppress RAG-1. Despite their presumably high proliferation potential, 27/44DP cells rarely dominate in leukemia. At 44SP stage, which corresponds to TEL/AML1(neg) leukemias, RAG-1 is reexpressed and Ig light chain gene starts to be rearranged.
- MeSH
- antigeny CD27 biosyntéza fyziologie genetika MeSH
- antigeny CD44 biosyntéza fyziologie genetika MeSH
- dítě MeSH
- financování organizované MeSH
- genová přestavba B-lymfocytů imunologie MeSH
- imunofenotypizace MeSH
- leukemie B-buněčná diagnóza genetika imunologie MeSH
- lidé MeSH
- lymfopoéza genetika imunologie MeSH
- prekurzorové B-lymfoidní buňky cytologie imunologie patologie MeSH
- vývojová regulace genové exprese MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- Publikační typ
- srovnávací studie MeSH
