The immunophenotype of different immature, myeloid and B-cell lineage-committed CD34+ hematopoietic cells allows discrimination between normal/reactive and myelodysplastic syndrome precursors

Abstract

Occurrence of phenotypic abnormalities in CD34þ hematopoietic progenitor and precursor cells (HPC) and their major B-cell and nonlymphoid compartments has been frequently reported in myelodysplastic syndromes (MDS). Here, we analyze for the first time the numerical and phenotypic abnormalities of different maturation-associated subsets of bone marrow (BM) CD34þ HPC from 50 newly diagnosed MDS patients in comparison to normal/reactive BM (n ¼ 29). Our results confirm the existence of heterogeneously altered phenotypes among CD34 þ HPC from MDS and indicate that such variability depends both on the relative distribution of the different subsets of CD34 þ HPC committed into the different myeloid and B-lymphoid compartments, and their immunophenotype (for example, higher reactivity for CD117 and CD13 and lower expression of CyMPO, CD64 and CD65 on CD34 þ immature and neutrophil precursors), a clear association existing between the accumulation of CD34 þ HPC and that of immature CD34 þ HPC. Interestingly, expansion of erythroidand neutrophil-lineage CD34 þ cells is detected in low-grade MDS at the expense of CD34 þ plasmacytoid dendritic cell and B-cell precursors, while expansion of immature CD34 þ precursors occurs in high-grade MDS. On the basis of the number and severity of the phenotypic abnormalities detected, a scoring system is proposed that efficiently discriminates between normal/reactive and MDS CD34 þ HPC, the mean score significantly increasing from low-to high-grade MDS.

A systematic analysis of bone marrow cells by flow cytometry defines a specific phenotypic profile beyond GPI deficiency in paroxysmal nocturnal hemoglobinuria

“…As already described by several reports [11][12][13][14], one finding emerging from our study concerned precursor B cells, not detectable in the majority (70%) of MDS patients. Furthermore, several alterations emerged in MDS within CD34þ and mature compartments.…”

“…Our approach was adapted from the one described by Matarraz et al [13]. Briefly, some major BM cell compartments were identified on the basis of forward (FSC) and sideward (SSC) light scatter characteristics and their reactivity for CD45 and CD34 ( Figs 1A,B,D,E,G,H).…”

“…In fact, it includes the study of GPI-related molecules on red cells and it is performed on peripheral blood (PB), whose analysis is less prone to be misinterpreted than on BM, due to the dependency on maturation of some GPIrelated antigens. Many reports have proposed FC as a useful technique in the diagnosis of MDS, mainly by investigating the expression of key antigens during maturation [11][12][13][14][15]. Such an approach on BM samples in view of cytopenia may not be able to distinguish PNH from MDS.…”

Insights into the cellular origin and etiology of the infant pro-B acute lymphoblastic leukemia with MLL-AF4 rearrangement

“…We therefore addressed whether pDC CD34 þ precursors coexpress NG2. Interestingly, we found that 12.2% of the pDC precursors (CD34 þ /CD45 þ /CD38 þ / CD123 high /HLADR þ ) [65][66][67] readily coexpress NG2 (Figure 2c). This suggests that, regardless of the status of the MLL locus, the NG2 antigen may be expressed in pDC leukemias if the leukomogenesis process is initially triggered in a pDC CD34 þ precursor readily expressing NG2, which might act as a leukemic-initiating cell.…”

The impact of cytomorphology, cytogenetics, molecular genetics, and immunophenotyping in a comprehensive diagnostic workup of myelodysplastic syndromes

“…Hierarchical clustering of flow cytometry data with different subsets of hematopoietic progenitor and precursor cells allowed discrimination of cases with normal bone marrow from MDS RAEB-2 in all cases, and a predictive lower value was obtained for the separation of patients with MDS subtypes RA, RCMD, or MDS RAEB-1 from cases with normal bone marrow. 35 Furthermore, clonal chromosomal aberrations were detected in 14.3% in the group being classified as MDS by flow cytometry, whereas cytomorphology produced no suspicion of MDS. Therefore, it was demonstrated that immunophenotyping could diagnose MDS in some cases that were not detectable by cytomorphological criteria.…”