Effect of red cell exchange transfusion on plasma levels of inflammatory mediators in sickle cell patients with acute chest syndrome

Abstract

Red cell exchange transfusion is the recommended therapy for patients with sickle cell disease (SCD) who have severe, progressive acute chest syndrome (ACS). A double-volume red cell exchange transfusion decreases the percentage of hemoglobin S (Hgb S) containing red blood cells to less than 20%, improving vascular perfusion. We speculated that reduction of pro-inflammatory mediators might also contribute to the therapeutic effect of an exchange transfusion. We measured white blood cell count (WBC), absolute neutrophil count (ANC), platelet concentration as well as plasma levels of interleukin-1alpha (IL-1alpha), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interleukin-8 (IL-8), and soluble vascular cell adhesion molecule-1 (sVCAM-1) in 8 sickle cell patients with 9 episodes of ACS who received a manual, double-volume exchange transfusion. Six patients with SCD seen during a routine clinic visit were used as controls. The mean number of hospitalization days was 6, with an average of 2 days in the intensive care unit. All patients recovered without complication. Sickle cell patients with ACS had a higher WBC and ANC at baseline but lower sVCAM-1 levels compared to controls. TNF-alpha, IL-1alpha, IL-1beta, and IL-8 levels were not significantly different from controls. WBC, ANC, platelet, and sVCAM-1 measurements were significantly decreased immediately post-exchange in patients with ACS; however, this effect was not persistent as levels trended towards pre-exchange values by 24 hr post-exchange. Due to wide inter-individual variability, a consistent pattern was not seen for TNF-alpha, IL-1alpha, IL-1beta, or IL-8. We conclude that in sickle cell patients with ACS, a manual, double-volume exchange transfusion lowers WBC, ANC, platelets, and sVCAM-1 levels, but the effect is short-lived.