Contributions of flow cytometry in the evaluation of myelodysplastic syndrome patients

Background: Myelodysplastic syndromes (MDS) are a group of malignant myeloid hematopoietic disorders. The diagnosis of MDS can be difficult, especially in cases with a low blast count and a normal karyotype. Flow cytometry has been used to distinguish MDS from nonclonal cytopenias. No one single simple flow cytometric parameter has been proposed to be diagnostic of MDS. Aim: The aim of the present study was to evaluate immunophenotypic alterations in typical MDS patients and whether these abnormalities help in the differentiation process between MDS with nonclonal disorder and leukemic patients. Materials and methods: Marrow aspirates from 29 patients, including 13 with MDS, 16 with acute myeloid leukemia, and 18 with nonclonal disorders (normal controls), were examined in this study. Their immunophenotypes were analyzed using flow cytometry. Blasts, nonblast myeloid cells, and monocytes were gated on the basis of CD45 expression and side scatter (SSC). Results: Comparison among the three groups showed that the granulocytic lineages of MDS showed decreased SSC compared with the controls (P 0.005 and P 0.000, respectively), altered CD45 intensity (P 0.004), decreased CD10-positive granulocytes (P 0.02), and a higher CD56 positive expression in the MDS and leukemic group (P 0.05 and P 0.001, respectively). Also, decreased intensity of CD11b (P 0.03) was observed in the MDS group. The expression rate of CD123+ was significantly higher in MDS patients than that in normal controls (P 0.0001). Conclusion: Gating of the granulocytic region is a relatively easy method for MDS immunophenotyping. Among the parameters studied, SSC, CD10, CD123, and CD56 were the most useful for differentiating MDS from nonclonal disorders, whereas immunophenotypic changes in MDS appear to be useful for differentiating MDS from nonclonal disorders.