Endothelial and peripheral blood cell activation in β-thalassemia children

Background: Increased adhesive events between endothelium and peripheral blood cells play a central role in the initiation of thromboembolic events that frequently complicate the outcome of β-thalassemia.Aim: The aim of the study was to evaluate endothelial activation/dysfunction and activation of peripheral blood cells in children with β-thalassemia and to correlate endothelial and cellular activation markers with other hematological parameters in the same cohort, and to find out if these markers could be used as parameters that predict vascular complications in these patients.Participants and methods: Endothelial adhesion molecules [intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin adhesion molecule (ELAM)], and endothelin-1 (ET-1) were analyzed using immunoassays. Early activation antigen (CD69) expression on the peripheral blood leukocytes was detected using a flow cytometer in 55 β-thalassemics [30 major (β-TM); 15 intermedia (β-TI), and 10 minor] and 25 healthy age-matched and sex-matched children.Results: The levels of sICAM-1, sVCAM-1, ELAM, and ET-1 in β-TM and β-TI were significantly higher than those in thalassemia minor and controls. The levels of sVCAM-1 were significantly increased in splenectomized patients (P 0.001). Serum ICAM-1, sVCAM-1, and ELAM levels were positively correlated to each other in the β-TM and β-TI groups, with a significant difference (P 0.05). ET-1 was positively correlated to sVCAM-1 in the β-TM group. Ferritin was positively correlated to serum ICAM-1, VCAM-1, and ELAM in β-TM and β-TI. In β-thalassemia minor, ferritin was positively correlated only with serum ICAM-1 and VCAM-1. The expression of CD69 on leukocytes was significantly greater in β-TM, followed by β-TI and then β-thalassemia minor than the control groups. In the thalassemia minor group, CD69 expression was upregulated on monocytes, but neither on neutrophils nor on lymphocytes compared with the controls. There was no significant change in CD69 levels among splenectomized and nonsplenectomized patients. ET-1 levels were significantly correlated to CD69 expression on lymphocytes of the β-TM group.Conclusion: Endothelial activation markers and activated leukocytes are significantly increased in β-thalassemics, showing that a severe degree of endothelial activation and damage along with chronic inflammation underlie the pathophysiology of vascular complications in these patients. The parameters studied might be useful markers for the follow-up of the vascular disease and may pave the way for improvements in the therapies for this disease.