Side Scatter Level of Main Populations in Peripheral Blood using Flow Cytometry as a Tool for the Screening/Detection of Dysplasia and Its Utility in the Diagnosis of Myelodysplastic Syndromes
Authors: Rusanova Ekaterina , Simon-Lopez Ramon 
Published: April 2020

Abstract
The myelodysplastic syndromes (MDS) are a group of clonal bone marrow disorders characterized by peripheral cytopenias, ineffective hematopoiesis, and unilineage or multilineage dysplasia. The feature used commonly for the diagnostic of MDS includes several morphological cell characteristics such as the presence of hypogranulation in the neutrophils. We have observed in our daily experience at the Mean Scatter of neutrophils was lower in MDS than in normal cases. We have observed that Lymphocyte scatter is quite constant in normal cases and in the majority of MDS. 11 patients diagnosed with MDS and 16 normal blood donors as a control group were enrolled into this study. The protocol of study included evaluation of blood cell populations by hematological analyzer GenS (BC), smears microscopy and flow cytometry for identification a level of granularity of neutrophils (FC500, BC). We created a single tube protocol for immunophenotyping of blood cells by multiparametric flow cytometry using a panel of monoclonal antibodies: CD14-FITC, CD16-PE, CD33-PC5 and CD45-PC7 (BC). We isolated the neutrophil and the lymphocyte populations by subsequent gating steps according to FS/SS, CD45/SS, CD45/CD16 and CD33/CD14. After gating, we measured the Mean Side Scatter in lymphocytes and neutrophils. In order to standardize the NE Mean Scatter we used also a ratio that was calculated by dividing the Neutrophil Mean Scatter by Lymphocyte Mean Scatter.
Descriptive Statistics
Mean Scatter n Mean SD Median Normals 16 633.6 99.7 612 MDS 11 564.4 83.1 543
Comparative Statistics
Normals vs MDS T-test Mean differences ROC AUC ROC cut-off sensitivity specificity sign. ROC Mean NE Scatter 0.071 69.11 0.685 &lt;=543 54.5 87.5 0.0732 Ratio NES/LYS 0.016 2.175 0.824 &lt;=8.34 81.82 81.25 0.0001
The results show the consistent differences between the Neutrophil Mean Scatter in the MDS group compared with the normals with a p =0.07 near the level of statistical significance.
The Ratio between Mean Scatter of Neutrophils and the Mean Scatter of Lymphocytes (Ratio NE S/LY S) was significantly lower in MDS than in the group of normals (p=0.016).
The ROC Curve analysis using the Neutrophil Mean Scatter to detect/flag MDS showed an acceptable area under the curve AUC=0.685 (significance level 0.073) with a cut-off of &lt;=533 we obtain a sensitivity of 54.5% with a specificity of 87.5%.
The ROC Curve analysis using the Ratio NE S/LY S to detect/flag MDS have shown a good area under the curve AUC=0.824 (significance level 0.0001) with a cut-off of &lt;=8.34 we obtain a sensitivity of 81.8% with a specificity of 81.2%.
The fact about hypogranularity of the neutrophils is a well known feature of MDS. Using the Neutrophil Mean Scatter and the Ratio between Mean Scatter of Neutrophils and the Mean Scatter of Lymphocytes may be useful tool to detect or flag the neutrophil hypogranularity and will permit to help in the differential diagnosis of MDS. These data are numerical, quantitative and objective. It will be necessary to increase the number of cases (MDS) and to include other hematologic malignancies in order to see the specificity of this findings compared with other diseases.