Altered Functional Properties of Eosinophils In Sickle Cell Anemia and Effects of Hydroxyurea Therapy

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2656-2656
Author(s):  
Flavia Rubia Pallis ◽  
Nicola Conran ◽  
Kleber Yotsumoto Fertrin ◽  
Sara T. Olalla-Saad ◽  
Fernando Ferreira Costa ◽  
...  
Keyword(s):  
Functional Properties ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Peripheral Blood ◽  
Plasma Levels ◽  
Transgenic Animal ◽  
Healthy Controls ◽  
Eosinophil Peroxidase

Abstract Abstract 2656 The pathophysiology of sickle cell anemia (SCA) is now recognized to include a chronic inflammatory condition that contributes to the recurrent episodes of vaso-occlusion that characterize this disease. The vaso-occlusive process is a multi-step process that involves different cell types, such as red blood cells, reticulocytes, activated endothelial cells, platelets and leukocytes. In vivo transgenic animal studies indicated that the neutrophil appears to be the most important leukocyte in vaso-occlusion in previous transgenic animal in vivo studies; however, eosinophils (EOs) may also participate in this phenomenon in humans. EOs are found in significantly elevated numbers in sickle cell disease individuals and, in static adhesion assays, demonstrate augmented adhesive properties suggesting an activated state of these cells. However, the role of EOs in the pathophysiology of SCD and the effect of hydroxyurea (HU) therapy on the functional properties of these cells are not well understood. The aim of this study was to evaluate EO adhesion, migration and degranulation in SCA patients and the effect of HU therapy on these cells. EOs were purified from the peripheral blood of healthy controls (CON) (n≥10), steady-state SCA patients (n≥12) and SCA patients on HU therapy (n≥15), using Percoll gradient separation, followed by immunomagnetic sorting. EO adhesion was determined by static adhesion assays and degranulation was evaluated by measurement of eosinophil peroxidase activity. Migration of EOs was determined in 96-multiwell chemotaxis chamber assays. Plasma levels of Eotaxin-1, 2 and RANTES, important eosinophil attracting chemokines, were determined by ELISA. The absolute number of EOs in the peripheral blood of SCD patients not treated with HU was significantly higher compared to control individuals (0.504±0.09 vs 0.188±0.04; P=0.01, respectively). SCA patients taking HU presented significantly lower numbers of EOs (0.200±0.05, P = 0.01). Basal adhesion of EOs from SCA patients was significantly higher than in healthy controls (22.8±2.6 vs 13.7±1.7%, respectively, P = 0.004). Furthermore, the EOs from SCA patients on HU therapy demonstrated a significantly lower adhesion to fibronectin (12.5±2.0%, P=0.002). Spontaneous EO chemotaxis was significantly increased in SCA patients, compared to healthy controls (12.9±1.56 vs 6.97±0.8 × 105/ml, respectively, P=0.009). Interestingly, the chemotatic response of EOs isolated from SCA patients taking HU was also higher than that of control EOs (12.1± 1.9 × 105/ml). EO chemotaxis in response to RANTES, Eotaxin and IL5 was significantly augmented in all groups compared to spontaneous chemotaxis (RANTES: CON: 15.3± 2.3; SCA: 19.9±3.0; SCAHU: 25.0±4.7; Eotaxin: CON: 18.7±3.0; SCA: 24.5±4.2; SCAHU: 24.0±5.2; IL5: CON: 13.4±2.4; SCA: 18.8±3.0, SCAHU: 16.6±4.5, P<0.05). Baseline eosinophil peroxidase release was higher in SCA EOs, compared to CON EOs (0.4±0.04 vs 0.2±0.02, respectively, P=0.001), but patients on HU presented a lower EOs degranulation than SCA not on HU (0.19±0.03, P=0.003). Plasma levels of Eotaxin-1 and RANTES were significantly higher in SCA individuals, compared to CON individuals (124±7; 1057±125 vs 78±7; 540±50.2 pg/ml, P=0.0002; P=0.0009, respectively). HU therapy was not associated with any change in Eotaxin-1 and RANTES plasma levels (117.9±9.7; 1175±126.2 pg/ml, respectively). Eotaxin-2 plasma levels did not vary among groups (485±80.8, 450±34, 398±47.8 pg/ml for CON, SCA and SCAHU, respectively). EOs of patients with SCA demonstrate a higher capacity for spontaneous migration, stimulated migration and degranulation. Therapy with HU is associated with reduced adhesion and degranulation of EOs in these patients, but had no effect on the chemotactic ability of these cells or chemokine levels. The presence of relative eosinophilia along with altered functional properties in SCA patients warrants further investigation of the role of EOs in the vaso-occlusive process. In particular, complications associated with allergic reactions, such as acute thoracic syndrome and asthma in SCA children, in which EO adhesion and degranulation may be more important, should be studied. The characteristics of the effect of HU on EO also suggest that SCA events in which EO chemotaxis plays a role are likely to respond poorly to HU therapy, and should lead to the development of alternative therapeutic strategies. Disclosures: No relevant conflicts of interest to declare.

In Vitro and In Vivo Antioxidant Effect of Fermented Papaya Preparation (FPP) on Blood Cells of Beta-Thalassaemia Patients.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1766-1766
Author(s):  
Eitan Fibach ◽  
Johnny Amer ◽  
Ada Goldfarb ◽  
Eliezer Rachmilewitz
Keyword(s):  
Oxidative Stress ◽  
Lipid Peroxidation ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Peripheral Blood ◽  
Thalassemia Major ◽  
Oxidative Status ◽  
Beta Thalassemia ◽  
Thalassemia Intermedia

Abstract In sickle cell anemia (SCD) and thalassemia, although the basic lesions are mutations in the globin genes, the pathophysiology involves oxidative stress-mediated cell damage in the bone marrow (ineffective erythropoiesis due to apoptosis of early erythroid precursors) and in the peripheral blood (chronic hemolysis of mature RBC). In addition, some patients develop thromboembolic complications and recurrent bacterial infections, the etiology of which is related at least in part, to documented oxidative stress in platelets and neutrophils (PMN), respectively. To study the presence and the role of oxidative stress in thalassemia and SCD, we adapted flow cytometry techniques for measuring the generation of Reactive Oxygen Species (ROS), the content of reduced glutathione (GSH), membrane lipid peroxidation and externalization of phosphatidylserine (PS) moieties in RBC, platelets and PMN. Cells derived from the peripheral blood of patients with beta-thalassemia major, intermedia or SCD showed increased oxidative status (increased ROS, lipid peroxidation and PS externalization, and decreased GSH) compared with their normal counterparts. Incubating fresh blood samples from patients with thalassemia major and thalassemia intermedia with 10 mg/ml FPP for 16 hours at 37oC reduced the oxidative status of RBC as well as platelets and PMN. Experiments carried out in normal and thalassemic mice (Th3/+, a mouse model of human beta-thalassemia intermedia demonstrated that mice treated for one week with 10 mg/ml FPP (dissolved in the drinking water) had reduced oxidative stress compared to control mice. The in-vivo effect of FPP was tested on 9 patients with beta-thalassemia (6 - major and 3 - intermedia) treated with 3 gr FPP per os three times a day for 12–15 weeks. Following the treatment, the ROS in RBC, platelets and PMN decreased and the GSH increased in all patients (see table). Six of these patients responded by a modest increase in RBC, reticulocytes and hemoglobin levels. These results suggest that FPP may have an important clinical efficacy as an antioxidant in thalassemia and sickle cell anemia. The in vivo effect of FPP treatment of beta-thalassemia patients Baseline After treatment n Mean ± SE Mean ± SE P-value* * Paired samples t-test RBC 9 324.07 ± 29.19 209.55 ± 23.65 0.001 ROS Platelets 9 223.73 ± 26.49 109.11 ± 8.71 0.001 PMN 9 222.72 ± 46.42 117.61 ± 8.98 0.045 RBC 9 55.37 ± 5.37 94.88 ± 3.71 0.001 GSH Platelets 9 59.41 ± 4.98 97.55 ± 5.26 <0.0001 PMN 9 58.29 ± 5.35 90.06 ± 5.87 0.005

scholarly journals Abnormal Cytokine Production By Mast Cell Cultures from Sickle Cell Anemia Patients in Response to Inflammatory Stimuli and to Co-Culture with Eosinophils

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3566-3566
Author(s):  
Myriam Salazar-Terreros ◽  
Kleber Yotsumoto Fertrin ◽  
Nicolas Moreno Reyes ◽  
Fernando Ferreira Costa ◽  
Carla F. Franco-Penteado
Keyword(s):  
Mast Cell ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Peripheral Blood ◽  
Cytokine Production ◽  
Fold Increase ◽  
Individual Response ◽  
Activated State

Mast cell function (MC) in pathologic states can be studied through their ability to secrete mediators in vitro depending on MC phenotype and the nature of the stimuli. Reports on MC mediators in sickle cell anemia (SCA) patients are scarce, but clinical signs of MC activation syndrome, such as increased plasma histamine in vaso‐occlusive crisis (VOC), and normal or slightly elevated serum tryptase have been reported. However, assessing the biological relevance of MC as a cytokine source is more challenging because it is unclear under which circumstances they secrete those products in vivo, or if the cytokines measured systemically stem from a different cell type. We aimed to investigate the profile of mediators involved in the inflammatory process produced by MC in SCA. Methods:The supernatant of 5-week old MC cultures (17 SCA, 8 HV) obtained from peripheral blood CD34+ cells from 29 SCA patients and 13 healthy volunteers (HV) was analyzed using a multiplex platform and colorimetric assays for endothelin-1 (ET-1) and substance P (SP) (10 SCA, 6 HV). A correlation matrix (Pearson correlations, R software, v. 3.6.1) was generated using laboratory and clinical data chosen based on their value as inflammatory or prognosis markers (hydroxyurea [HU] treatment, fetal hemoglobin [HbF], hemoglobin [Hb], vaso-occlusive crisis [VOC], percentage of peripheral blood neutrophils, eosinophils (Eos), basophils, erythroblasts, and reticulocytes), MC surface expression of CD117, CD48 and CD63, and the supernatant content of 11 cytokines. To investigate MC cytokine release, we tested the supernatants from Eos-MC co-cultures (3:1 ratio), and after stimulation with ET-1 (20 nM), SP (10 µM) and imatinib (20 µg/ml)(n=3 per treatment). Results: Out of 26 cytokines, we found elevated levels of the following in the supernatants of SCA-MC cultures (data represented as mean in pg/ml±SE): TNFα: SCA=88.7±18.4, HV=32.6±3.8; IFNγ: SCA=55.3±11.2, HV=15.7±1.8; MCP1: SCA=555.0±147.2, HV=145.3±35.2; RANTES: SCA=24.7±3.9, HV=10.7±1.8 (p&lt;0.05). However, SCA-MC from patients treated with HU (n = 11) showed higher values of IL-1b, IL-4, IL-5, IL-9, IL-15, and FGF than HV (n=8) and HU-free patients (n=6) (p&lt;0.05). Supernatants from SCA-MC had higher ET-1 production compared to HV-MC (SCA=16.3±1.2, HV=11.93±1.3, pg/ml, p=0.02) but SP production was similar (SCA=27.9±1.3; HV=31.49±0.7 pg/ml). ET-1 stimulation of MC cultures caused 2-fold increase in IL-1AR production on HV-MC, but failed to produce any effect on SCA-MC. Similarly, imatinib reduced FGF only in HV-MC samples (HV: 15.1±3.5, HV-HU: 4.0±1.6, pg/ml). No effect on cytokine production was observed with SP. Conversely, Eos-MC cocultures showed a 10- and 4-fold increase of IL-5 and IL-9, respectively, regardless of the origin of Eos (HV or SCA). SCA-MC/SCA-Eos co-cultures had elevated proinflammatory (IL-1b, IL-12, TNF-α) and angiogenic (FGF, VEGF) cytokines, RANTES, IL-7, IL-4, and IL1-RA compared with SCA-MC/HV-Eos and HV-MC/HV-Eos (p&lt;0.05). Preliminary multiparametric analysis on data from SCA patients showed a strong negative correlation between HU therapy and VGEF production, and between HbF levels and CD63 expression (MC activation marker).We also found a positive correlation between history of VOC and eotaxin-1 produced by SCA-MC. Conclusions: We found that MC responses depend both on the origin of the cultured cell and the stimuli utilized. Despite differences between in vitro and in vivo MC populations, our data show that cultured SCA-MC have a sustained activated state and produce a repertoire of mediators that could contribute to a perivascular microenvironment in favor of leukocyte and endothelium activation. In terms of cytokine production, cultured SCA-MC were more sensitive to stimulation by SCA-Eos than by HV-Eos, which may be relevant to the pathophysiology of airway inflammation in SCA patients with asthma. Differences in cytokine production between SCA-MC cultures from patients treated or not with HU may reflect the variability in adherence to treatment, individual response to each compound, or epigenetic modifications during the MC differentiation process that affect the phenotype of the mature MC. These results support that mediators produced by MC can contribute to the chronic inflammatory state and may be implicated in exacerbated responses to eosinophil activation in SCA. Disclosures Fertrin: Agios Pharmaceuticals, Inc.: Research Funding.

The orientation of sickle hemoglobin fibers within fascicles

1988 ◽  
Vol 46 ◽  
pp. 400-401
Author(s):  
Christopher A. Miller ◽  
Bridget Carragher ◽  
William A. McDade ◽  
Robert Josephs
Keyword(s):  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Relative Orientation ◽  
Unit Cell ◽  
Red Cell ◽  
High Ph ◽  
Sickle Hemoglobin ◽  
Polar Crystal ◽  
Helical Configuration

Highly ordered bundles of deoxyhemoglobin S (HbS) fibers, termed fascicles, are intermediates in the high pH crystallization pathway of HbS. These fibers consist of 7 Wishner-Love double strands in a helical configuration. Since each double strand has a polarity, the odd number of double strands in the fiber imparts a net polarity to the structure. HbS crystals have a unit cell containing two double strands, one of each polarity, resulting in a net polarity of zero. Therefore a rearrangement of the double strands must occur to form a non-polar crystal from the polar fibers. To determine the role of fascicles as an intermediate in the crystallization pathway it is important to understand the relative orientation of fibers within fascicles. Furthermore, an understanding of fascicle structure may have implications for the design of potential sickling inhibitors, since it is bundles of fibers which cause the red cell distortion responsible for the vaso-occlusive complications characteristic of sickle cell anemia.

Plasminogen Activation In Vivo upon Intravenous Infusion of DDAVP

1992 ◽  
Vol 67 (01) ◽  
pp. 111-116 ◽  
Author(s):  
Marcel Levi ◽  
Jan Paul de Boer ◽  
Dorina Roem ◽  
Jan Wouter ten Cate ◽  
C Erik Hack
Keyword(s):  
Monoclonal Antibodies ◽  
Plasminogen Activator ◽  
Plasma Levels ◽  
Fold Increase ◽  
Fibrinolytic System ◽  
Plasminogen Activation ◽  
Plasminogen Activator Activity ◽  
Insight Into

SummaryInfusion of desamino-d-arginine vasopressin (DDAVP) results in an increase in plasma plasminogen activator activity. Whether this increase results in the generation of plasmin in vivo has never been established.A novel sensitive radioimmunoassay (RIA) for the measurement of the complex between plasmin and its main inhibitor α2 antiplasmin (PAP complex) was developed using monoclonal antibodies preferentially reacting with complexed and inactivated α2-antiplasmin and monoclonal antibodies against plasmin. The assay was validated in healthy volunteers and in patients with an activated fibrinolytic system.Infusion of DDAVP in a randomized placebo controlled crossover study resulted in all volunteers in a 6.6-fold increase in PAP complex, which was maximal between 15 and 30 min after the start of the infusion. Hereafter, plasma levels of PAP complex decreased with an apparent half-life of disappearance of about 120 min. Infusion of DDAVP did not induce generation of thrombin, as measured by plasma levels of prothrombin fragment F1+2 and thrombin-antithrombin III (TAT) complex.We conclude that the increase in plasminogen activator activity upon the infusion of DDAVP results in the in vivo generation of plasmin, in the absence of coagulation activation. Studying the DDAVP induced increase in PAP complex of patients with thromboembolic disease and a defective plasminogen activator response upon DDAVP may provide more insight into the role of the fibrinolytic system in the pathogenesis of thrombosis.

scholarly journals Role of Calcium in Phosphatidylserine Externalisation in Red Blood Cells from Sickle Cell Patients

Anemia ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Erwin Weiss ◽  
David Charles Rees ◽  
John Stanley Gibson
Keyword(s):  
Red Blood Cells ◽  
Sickle Cell ◽  
Blood Cells ◽  
Phosphatidylserine Exposure ◽  
Channel Inhibition ◽  
Cation Conductance ◽  
Gardos Channel ◽  
Cation Permeability

Phosphatidylserine exposure occurs in red blood cells (RBCs) from sickle cell disease (SCD) patients and is increased by deoxygenation. The mechanisms responsible remain unclear. RBCs from SCD patients also have elevated cation permeability, and, in particular, a deoxygenation-induced cation conductance which mediates entry, providing an obvious link with phosphatidylserine exposure. The role of was investigated using FITC-labelled annexin. Results confirmed high phosphatidylserine exposure in RBCs from SCD patients increasing upon deoxygenation. When deoxygenated, phosphatidylserine exposure was further elevated as extracellular [] was increased. This effect was inhibited by dipyridamole, intracellular chelation, and Gardos channel inhibition. Phosphatidylserine exposure was reduced in high saline. levels required to elicit phosphatidylserine exposure were in the low micromolar range. Findings are consistent with entry through the deoxygenation-induced pathway (), activating the Gardos channel. [] required for phosphatidylserine scrambling are in the range achievablein vivo.

Role of adenosine in noradrenergic neurotransmission in spontaneously hypertensive rats

1987 ◽  
Vol 253 (4) ◽  
pp. H909-H918 ◽  
Author(s):  
E. K. Jackson
Keyword(s):  
Plasma Levels ◽  
Spontaneously Hypertensive Rat ◽  
Base Line ◽  
Inhibitory Effects ◽  
Spontaneously Hypertensive ◽  
Vascular Responses ◽  
Rat Mesentery ◽  
Wistar Kyoto

The purpose of this study was to compare the in vivo role of adenosine as a modulator of noradrenergic neurotransmission in the spontaneously hypertensive rat (SHR) and Wistar-Kyoto control rat (WKY). In the in situ blood-perfused rat mesentery, vascular responses to periarterial (sympathetic) nerve stimulation (PNS) and to exogenous norepinephrine (NE) were enhanced in SHR compared with WKY. In both SHR and WKY, vascular responses to PNS were more sensitive to inhibition by adenosine than were responses to NE. At matched base-line vascular responses, compared with WKY, SHR were less sensitive to the inhibitory effects of adenosine on vascular responses to PNS, but SHR and WKY were equally sensitive with respect to adenosine-induced inhibition of responses to NE. Antagonism of adenosine receptors with 1,3-dipropyl-8-p-sulfophenylxanthine shifted the dose-response curve to exogenous adenosine sixfold to the right yet did not influence vascular responses to PNS or NE in either SHR or WKY. Furthermore, PNS did not alter either arterial or mesenteric venous plasma levels of adenosine in SHR or WKY, and plasma levels of adenosine in both strains were always lower than the calculated threshold level required to attenuate neurotransmission. It is concluded that in vivo 1) exogenous adenosine interferes with noradrenergic neurotransmission in both SHR and WKY; 2) SHR are less sensitive to the inhibitory effects of exogenous adenosine on noradrenergic neurotransmission than are WKY; 3) endogenous adenosine does not play a role in modulating neurotransmission in either strain under the conditions of this study; and 4) enhanced noradrenergic neurotransmission in the SHR is not due to defective modulation of neurotransmission by adenosine.

scholarly journals Sickle Cell Anemia and Babesia Infection

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1435
Author(s):  
Divya Beri ◽  
Manpreet Singh ◽  
Marilis Rodriguez ◽  
Karina Yazdanbakhsh ◽  
Cheryl Ann Lobo
Keyword(s):  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Current Knowledge ◽  
Globin Gene ◽  
Environmental Niche ◽  
Parasite Resistance ◽  
The Usa ◽  
Human Infections

Babesia is an intraerythrocytic, obligate Apicomplexan parasite that has, in the last century, been implicated in human infections via zoonosis and is now widespread, especially in parts of the USA and Europe. It is naturally transmitted by the bite of a tick, but transfused blood from infected donors has also proven to be a major source of transmission. When infected, most humans are clinically asymptomatic, but the parasite can prove to be lethal when it infects immunocompromised individuals. Hemolysis and anemia are two common symptoms that accompany many infectious diseases, and this is particularly true of parasitic diseases that target red cells. Clinically, this becomes an acute problem for subjects who are prone to hemolysis and depend on frequent transfusions, like patients with sickle cell anemia or thalassemia. Little is known about Babesia’s pathogenesis in these hemoglobinopathies, and most parallels are drawn from its evolutionarily related Plasmodium parasite which shares the same environmental niche, the RBCs, in the human host. In vitro as well as in vivo Babesia-infected mouse sickle cell disease (SCD) models support the inhibition of intra-erythrocytic parasite proliferation, but mechanisms driving the protection of such hemoglobinopathies against infection are not fully studied. This review provides an overview of our current knowledge of Babesia infection and hemoglobinopathies, focusing on possible mechanisms behind this parasite resistance and the clinical repercussions faced by Babesia-infected human hosts harboring mutations in their globin gene.

scholarly journals Severe sickle cell anemia is associated with increased plasma levels of TNF-R1 and VCAM-1

2011 ◽  
Vol 86 (2) ◽  
pp. 220-223 ◽  
Author(s):  
Daniel A. Dworkis ◽  
Elizabeth S. Klings ◽  
Nadia Solovieff ◽  
Guihua Li ◽  
Jacqueline N. Milton ◽  
...  
Keyword(s):  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Plasma Levels

Hydroxyurea corrects the dysregulated L-selectin expression and increased H2O2 production of polymorphonuclear neutrophils from patients with sickle cell anemia

Blood ◽  
2002 ◽  
Vol 99 (7) ◽  
pp. 2297-2303 ◽  
Author(s):  
Malika Benkerrou ◽  
Charlotte Delarche ◽  
Lamia Brahimi ◽  
Michèle Fay ◽  
Etienne Vilmer ◽  
...  
Keyword(s):  
Adhesion Molecules ◽  
Sickle Cell ◽  
Adhesion Molecule ◽  
Sickle Cell Anemia ◽  
Plasma Levels ◽  
Polymorphonuclear Neutrophil ◽  
H2o2 Production ◽  
Soluble Adhesion Molecules ◽  
Hydroxyurea Treatment ◽  
History Of

Impaired polymorphonuclear neutrophil (PMN) functions during sickle cell anemia (SCA) may have a pathogenic role in the onset of vasoocclusive events. We used flow cytometry to study, in whole blood, the adhesion molecule expression and respiratory burst of PMNs from children with SCA. Three different clinical groups were studied: (1) patients with no history of vasoocclusive events (n = 15); (2) patients with a history of vasoocclusive events (n = 17); and (3) patients receiving hydroxyurea therapy for severe vasoocclusive events (n = 9). Unstimulated PMNs showed decreased L selectin expression and increased H2O2 production whatever the severity of the disease, reflecting PMN activation. This could contribute to endothelial activation reflected by abnormal plasma levels of soluble adhesion molecules (soluble intercellular adhesion molecule-1, sE selectin, and sL selectin). After stimulation with bacterial N-formyl peptides (N-formyl-methionyl-leucyl-phenylalanine [fMLP]), PMNs from untreated patients with a history of vasoocclusive events showed dysregulated L selectin shedding and increased H2O2 production. Furthermore, in these patients, tumor necrosis factor priming followed by fMLP stimulation induced an H2O2 production significantly higher than in the other patient groups and controls. These impairments could immobilize PMNs on the endothelium, thereby inducing reduced blood flow and fostering microvascular occlusion and vascular damage. In contrast, children treated with hydroxyurea showed near-normal basal and poststimulation H2O2 production as well as normal L selectin shedding after stimulation but no change in plasma levels of soluble adhesion molecules. To our knowledge, this is the first report showing major qualitative changes of PMN abnormalities upon hydroxyurea treatment in SCA patients. This strongly suggests that PMNs are a primary target of this drug.

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