Differences of microparticle patterns between sickle cell anemia and hemoglobin SC patients.

Yohann Garnier,Maryse Etienne-Julan,Marie-Dominique Hardy-Dessources,Séverine Ferdinand,Marc Romana,Lydia Doumdo,Marie Petras,Gisèle Elana,Philippe Connes,Marie-Laure Lalanne-Mistrih,Benoit Tressières

doi:10.1371/journal.pone.0177397

Abstract

Sickle cell anemia (SCA) and hemoglobin SC (HbSC) disease are the two most common forms of sickle cell disease (SCD), a frequent hemoglobinopathy which exhibits a highly variable clinical course. Although high levels of microparticles (MPs) have been consistently reported in SCA and evidence of their harmful impact on the SCA complication occurrences have been provided, no data on MP pattern in HbSC patients has been reported so far. In this study, we determined and compared the MP patterns of 84 HbSC and 96 SCA children, all at steady-state, using flow cytometry. Most of circulating MPs were derived from platelets (PLTs) and red blood cells (RBCs) in the two SCD syndromes. Moreover, we showed that HbSC patients exhibited lower blood concentration of total MPs compared to SCA patients, resulting mainly from a decrease of MP levels originated from RBCs and to a lesser extent from PLTs. We did not detect any association between blood MP concentrations and the occurrence of painful vaso-occlusive crises, acute chest syndrome and pulmonary hypertension in both patient groups. We also demonstrated for the first time, that whatever the considered genotype, RBC-derived MPs exhibited higher externalized phosphatidylserine level and were larger than PLT-derived MPs.

Highlights

Sickle cell disease (SCD) is a group of genetic disorders having in common the production of the abnormal hemoglobin S (HbS) instead of hemoglobin A
We detected lower concentrations of total MP, red blood cells (RBCs)- and PLT-derived MP in hemoglobin SC (HbSC) patients compared to Sickle cell anemia (SCA) patients not treated by HC (4,587 (IQR 2,605–10,915) vs 12,155 MP/μl (IQR 5,916–19,510), p < 0.001; 260 (IQR 151–540) vs 755 MP/μl (IQR 401–1,782), p < 0.001; 4,014 (IQR 2,154–9,570) vs 8,643 MP/μl (IQR 4,383–15,697), p < 0.01, respectively) while no difference was detected between HbSC and HC-treated SCA patient
RBC- and PLT-derived MPs isolated from HbSC children exhibited higher mean fluorescence intensity (MFI) than those isolated from SCA children (p = 0.009 and p = 0.002 respectively)

Summary

Introduction

Sickle cell disease (SCD) is a group of genetic disorders having in common the production of the abnormal hemoglobin S (HbS) instead of hemoglobin A. Sickle cell anemia (SCA), i.e. the homozygous form of SCD, results from a single base mutation in exon 1 of the β-globin gene which causes the substitution of valine for glutamic acid at the sixth position of the β-globin chain. HbS polymerizes and induces the sickling of red blood cells (RBCs), leading to decreased deformability and increased fragility of these cells.

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