Brahimi et al., J Hematol Thromb Dis 2013, 1:4 DOI: 10.4172/2329-8790.1000e104 Volume 1 • Issue 4 • 1000e104 J Hematol Thromb Dis ISSN: 2329-8790 JHTD, an open access journal The Role of Flow Cytometry in the Diagnosis of Myelodysplasic Syndromes Mohamed Brahimi 1,2 *, Mohammed Nazim Bennaoum 1 , Hassiba Lazreg 1 , Affaf Adda 1 , Fadela Attaf 2 , Abdessamad Arabi 2 , Souf Osmani 2 , Nabil Yafour 2 and Mohamed Amine Bekadja 2 1 Department of Hemobiology, Institution University Hospital, Oran, Algeria 2 Department of Hematology and Cell Therapy, Institution University Hospital, Oran, Algeria *Corresponding author: Mohamed Brahimi, Department of Hemobiology, Institution University Hospital, 269 Hai, Ennakhla Canastel 31132 Oran, Algeria, Tel: 00213 771 48 57 39; Fax: 00213 41 42 16 36; E-mail: bmw73dz@yahoo.fr Received July 21, 2013; Accepted October 17, 2013; Published October 19, 2013 Citation: Brahimi M, Bennaoum MN, Lazreg H, Adda A, Attaf F, et al. (2013) The Role of Flow Cytometry in the Diagnosis of Myelodysplasic Syndromes. J Hematol Thromb Dis 1: e104 doi: 10.4172/2329-8790.1000e104 Copyright: © 2013 Brahimi M, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Myelodysplastic Syndromes (MDS) are a heterogeneous group of myeloid neoplasms characterized by dysplastic features of erythroid and/or myeloid and/or megakaryocytic lineages, a varying percentage of blast cells, progressive bone marrow failure and enhanced risk to evolve towards acute myeloid leukemia [1]. Te diagnosis of MDS is straightforward if an increase in blasts and/or ringed sideroblasts and/or presence of chromosomal aberration as evidence of clonal myelopoiesis, are detected. In other words, a diagnostic challenge exists in low-grade MDS without ringed sideroblasts with normal karyotype. For this reason many laboratory scientists have investigated the use of Flow Cytometry (FCM) to increase the sensitivity and specifcity of diagnosis in such cases [2]. Most authors examined bone marrow cells using multiparameter FCM, applying a pattern recognition approach [3]. As maturation and diferentiation of hematopoietic cells is abnormal in MDS, FCM identifes dysplasia by detecting deviations from the normal pattern of antigen expression [3,4]. Data interpretation is not based solely upon whether an antigen is ‘positive’ or ‘negative’. Instead, interpretation is based on the examination of staining patterns demonstrated by a series of antibody combinations. Tis approach requires an extensive knowledge of the normal patterns of antigen expression during diferentiation [3]. Te fow cytometric abnormalities typically detected in MDS include: abnormal co-expression of antigens that are normally present at diferent stages of diferentiation, abnormal intensity of antigen expression, presence of aberrant lymphoid lineage antigens expressed on myeloid precursors, and abnormally decreased side scatter properties due to hypo granularity of granulocytes [3]. In general, the antigens expressed on normal myeloid precursors (such as CD34, CD117, and HLA-DR) and those on immature granulocytes (such as CD13 and CD33) are increased in MDS. In contrast, antigens that are expressed on mature granulocytes (such as CD10, CD11b, CD11c, CD16, and CD64) are decreased in MDS [5]. Among all the quantitative changes, CD34 abnormality is most thoroughly studied. Te percentage of CD34 cells is usually proportional to the number of blasts. Terefore, its percentage increases progressively from RA and RARS to RAEB and leukemic transformation [6]. Qualitative changes are mainly manifested as aberrant expression of nonmyeloid markers, namely, T-cell, B-cell, and natural killer cell markers. CD7 and CD19 can be detected on maturing myeloid cells or monocytes [7]. CD56 may be found on myeloblasts and maturing myeloid cells and monocytes [7]. Abnormal patterns of CD11b versus CD16 expression or CD13 versus CD16 expression have also been identifed in MDS cases [3,7]. Finally, the low side-scatter property in the nonblastic myeloid cells in MDS cases represents the presence of hypogranular granulocytes [8]. Tis approach requires sufcient experience and knowledge of the normal (control) patterns of haematopoietic cells in FCM, which is the basis on which examiners identify abnormal MDS fow patterns. In other words, this approach is an FCM version of cytomorphology [2]. Obviously, there are many cases in which FCM patterns are intermediate between typical control patterns and typical MDS (A): All nucleated cells (R1) and cells with relatively low SSC (R2) are gated. (B): Cells in R2 in panel (A) are displayed on a CD45/CD34 plot, and CD34+ cells with intermediate CD45 expression are gated (R3). (C): Cells in the R3 gate are plotted on a CD45/SSC display. In the CD45/SSC dot plot, we can identify a cell population consisting predominantly of CD34+ B-cell progenitor cells which formed an easily recognizable cluster (R5) that had the lowest SSC and relatively low CD45 expression. Other CD34+ cells (R4) showing more SSC and a wider distribution of CD45 expression consisted predominantly of myeloblasts. (D) All nucleated cells are plotted on a CD45/SSC display. Histogram (D1) SSC of lymphocytes (in red) and granulocytes (in gray). SSC peak channel values (SSC channel number where the maximum number of cells occurs) of both fractions were computed. Histogram (D2) shows CD45 expression of lymphocytes (in red) and CD34+ myeloblasts (in cyan). Mean fuorescence intensity (MFI) of CD45 of both populations are computed. Figure 1: Ogata’s gating strategy cells stained with CD34 and CD45 antibodies [8-11]. J o u r n a l o f H e m a t o l o g y & T h r o m b o e m b o l i c D i s e a s e s ISSN: 2329-8790 Journal of Hematology & Thromboembolic Diseases Editorial Open Access