Bone marrow immunophenotyping by flow cytometry in refractory cytopenia of childhood

Abstract

Refractory cytopenia of childhood is the most common type of childhood myelodysplastic syndrome. Because the majority of children with refractory cytopenia have a normal karyotype and a hypocellular bone marrow, differentiating refractory cytopenia from the immune-mediated bone marrow failure syndrome (very) severe aplastic anemia can be challenging. Flow cytometric immunophenotyping of bone marrow has been shown to be a valuable diagnostic tool in differentiating myelodysplastic syndrome from non-clonal cytopenias in adults. Here, we performed the first comprehensive flow cytometric analysis of immature myeloid, lymphoid cells and erythroid cells, and granulocytes, monocytes, and lymphoid cells in bone marrow obtained from a large prospective cohort of 81 children with refractory cytopenia. Children with refractory cyotopenia had a strongly reduced myeloid compartment, but not as severe as children with aplastic anemia. Furthermore, the number of flow cytometric abnormalities was significantly higher in children with refractory cytopenia than in healthy controls and in children with aplastic anemia, but lower than in advanced myelodysplastic syndrome. We conclude that flow cytometric immunophenotyping could be a relevant addition to histopathology in the diagnosis of refractory cytopenia of childhood. (The multi-center studies EWOG-MDS RC06 and EWOG-MDS 2006 are registered at clinicaltrials.gov identifiers 00499070 and 00662090, respectively).

Trial registration: ClinicalTrials.gov NCT00499070 NCT00662090.

Copyright© Ferrata Storti Foundation.

Figures

Figure 1.

Cellular composition of bone marrow in refractory cytopenia of childhood patients and controls. For graphical representation, means of the main cell populations were calculated per patient and control group, and scaled to 100%. Precursors consist of myeloid blast cells and CD34+ B-cell precursors. NBM: normal bone marrow.

Figure 2.

Immunophenotype of immature erythroid cell, granulocytes, and monocytes in refractory cytopenia of childhood patients and controls. (A) Normal expression of CD71 in healthy control bone marrow, ID NBM 023. (B) Heterogeneous CD71 expression in RCC patient, ID CH028. (C) Heterogeneous CD71 expression in RCC patient, ID I 220. (D) Normal pattern of CD16-CD13 expression in healthy control bone marrow, ID NBM 023. (E) Abnormal pattern of CD16-CD13 expression in RCC patient, ID D 663. (F) Abnormal pattern of CD16-CD13 expression in RCC patient, ID D 555. (G) Absence or low level of CD56 expression on monocytes, indicated in orange, in healthy control bone marrow, ID NBM 023. Granulocytes and lymphocytes are indicated in pink and green, respectively. (H) Aberrant expression (>20%) of CD56 on monocytes in RCC patient, ID CZ078. (I) Aberrant expression (>20%) of CD56 on monocytes in RCC patient, ID SC126. Pink and orange lines indicate reference image of normal granulocytes and monocytes, respectively.

Figure 3.

Number of flow cytometric abnormalities in refractory cytopenia of childhood patients and controls. Lines indicate medians. Boxes extend from the 25th to 75th percentile; lines in the boxes indicate medians, whiskers indicate minimum and maximum values. **P<0.01; ****P<0.0001. NBM: normal bone marrow.