Differences in oxygen-gradient ektacytometry parameters and blood viscosity between patients with sickle cell anemia and patients with sickle cell-hemoglobin C disorder.

Oxygen-gradient ektacytometry (oxygenscan) has been recently used in the context of sickle cell disease (SCD) to determine the ability of red blood cells (RBCs) to deform in normoxia and during deoxygenation. While several studies focused on the determinants of oxygenscan parameters in the homozygous form of SCD (i.e., HbSS), very few studies focused on hemoglobin SC disease (HbSC). Oxygenscan parameters were compared between HbSS (N = 304) and HbSC (N = 58) patients, with or without hydroxyurea (HU). RBC deformability measured in normoxia or at low oxygen level was lower in HbSS patients without HU compared to HbSS patients with HU and HbSC patients with or without HU. The propensity of RBCs to sickle during deoxygenation was greater in HbSS than in HbSC patients. Although no significant impact of HU was observed on RBC deformability/sickling in HbSC patients, those with HU had lower blood viscosity. The ability of RBC to recover their maximum deformability after a deoxygenation/reoxygenation cycle was lower in HbSC compared to HbSS patients. Finally, oxygenscan parameters and routine hematological parameters correlated differently in HbSS and HbSC patients. Our study showed difference in oxygenscan parameters between HbSS and HbSC individuals that could partly explain the difference in the clinical expression of SCD.