Implication of the Oxydative Stress in the Pathophysiology of Sickle Cell Anemia:
Implication of the Oxydative Stress in the Pathophysiology of Sickle Cell Anemia:
Despite important advances in the current understanding of sickle cell vaso-occlusion, the
 basis of its control and prevention remain partially unknown. The primary purpose is to test
 the hypothesis of a control of the sickle cell vaso-cocclusive (VOC) process by the anti band
 3 antibodies by assessing the level of these antibodies in the steady state and during the
 crises in SCA patients. To assess the relationship between the level of band 3 antibodies,
 the oxidation status, the expression of microparticles and the hemorheological alterations of
 the sickle red cells (SS RBs), the severity of VOC.
Although oxidative stress is not the primary aetiology of SCA, oxidative damage could in part
 account for pathophysiological mechanisms leading to sickle vaso-occlusion, in which anti
 bande 3 antibodies might play a role. Bande 3 is a protein belonging to red blood cells.
 These anti bande 3 antibodies are producted when after oxidative damage, a hidden site of
 bande 3 is revealed. In preliminary data, the Cuban partner of this study showed a
 significative difference between their level in patients, during steady state and
 vaso-occlusive crises. Our clinical question is to determine if a decrease of these
 antibodies, could participate in the occurrence of the crises. Therapeutic strategies aimed
 to counteract oxidative abnormalities might alleviate this still nowadays unknown mechanisms
 disease progression.

 Band 3 protein which belongs to the anionic interchanger is the main erythrocyte membrane
 protein, present in about 1.2 x 106 copies per cell. Under certain conditions, band 3 protein
 modifications in the human erythrocyte membrane surface lead to band 3 aggregates. These
 modifications are mostly due to oxidative insults that gradually accumulate during red blood
 cell lifespan. Band 3 clusters on the SS RBCs produce two significant changes: first, these
 cells acquire an adhesive nature; second, band 3 aggregates are recognized by natural band 3
 antibodies. Several studies have shown that band 3 peptides are able to inhibit the adherence
 of SS RBCs to endothelial cells. This suggests possible participation of band 3 antibodies in
 the aethiology as well as in the prevention of VOC in SCA. Oxidant damage in RBCs may
 contribute to the circulatory disorders by affecting their flow properties i.e. their
 deformability, aggregability and adherence to endothelial cells. Therefore, in parallel of
 the study of the evaluation of the role of anti bande 3 antibodies in VOC occurrence and
 severity, the investigators will explore the involvement of oxidative stress on the
 rheological properties of SSRBCs (deformability and aggregability),
Inclusion Criteria:

 - adults ≥ 18 years old SCA patients (SS genotype) hospitalized for bone VOC with single or
 multifocal localizations.

 Exclusion Criteria:

 -  chronic transfusion therapy or recent blood transfusion (less than 3 months before the
 current VOC or the state defined "steady-state" in SCA);

 -  severe chronic renal failure; liver failure;

 -  autoimmune disease;

 -  viral hepatitis; HIV seropositivity;

 -  pregnancy or breast feeding;

 -  patients already engaged in another therapeutic clinical research protocol; -
 non-compliant patients to usual care;

 -  patients unable to give their consent.