RED BLOOD CELL DESIALYLATION, AS OBSERVED IN SEPSIS ALTERS THEIR SHAPE AND BIOCHEMISTRY

Introduction: Red blood cell (RBC) metabolism is totally dependent on glycolysis to supply the ATP required for the maintenance of ionic homeostasis and structural integrity (1). Several studies have observed interactions between glycolytic enzymes and the RBC membrane (2,3). We have recently observed that RBCs from septic patients show a more spherical shape with decreased membrane sialic acid (SA) content (4). Moreover, RBC sphericity was inversely correlated with membrane SA content (4). We therefore hypothesized that desialylation as observed in septic patients could alter RBC glycolysis. Materials and Methods: Washed RBCs from 9 volunteers (adjusted at 20% hematocrit) were incubated with 0.125 U/mL of neuraminidase from Clostridium perfringens or RPMI as controls. RBC shape was estimated by flow cytometry after 10 hours of incubation. Normal RBCs show a bimodal distribution related to the biconcave form (4). On this histogram, we calculated the second Pearson Coefficient of Dissymmetry (= 3 × (mean-median)/SD) (PCD). The normal PCD value is around - 0.8 and a null value represents a perfect spherical shape. To confirm the release of SA from the RBC membrane by neuraminidase, free SA concentrations in the supernatant were measured at baseline and after 10 hours of incubation by an enzymatic colorimetric assay. 2,3 DPG and RBC lactate concentrations were measured after 10 hours of incubation with neuraminidase. Data are presented as mean±SD and were compared by a Student's test; correlations were evaluated by a Spearman's test. Results: Neuraminidase altered RBC shape and glycolysis. PCD values were correlated with 2,3 DPG concentrations (r2 = 0.37; P = 0.008).TableConclusions: Desialylation induces RBC sphericity and an increase in RBC lactate and 2,3 DPG concentrations, already present 10 hours after neuraminidase treatment. These changes may play a role in the alterations in RBC rheology observed in sepsis, and could be the target of new interventions to improve the management of septic patients. Funds: Erasme Foundation