Increased circulating activated endothelial cells, vascular endothelial growth factor, and tumor necrosis factor in thalassemia

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Abstract
An increased number of circulating endothelial cells (CECs) was demonstrated in α- and β-thalassemic patients, β-thalassemia/hemoglobin E (BE), both splenectomized (BE[S]) and non-splenectomized (BE[NS]), had higher numbers of CECs than α-thalassemia, both HbH (α-thal l/α-thal 2; H) and HbH with hemoglobin Constant Spring (α-thal 1/CS; H/CS). CECs were also increased in heterozygous HbE (EA) and homozygous HbE (EE). The highest level of tumor necrosis factor-α (TNF-α) was found in HbH/CS patients, whereas the highest levels of vascular endothelial growth factor (VEGF) was observed in BE[S] patients. Significant decreases, in protein C and protein S levels were found in both α- and β-thalassemia compared with normal. Good correlations between the numbers of CEC and TNF-α, VEGF, protein C, and protein S levels were demonstrated in this study. In addition, markers for endothelial cell activation and injury (intercellular adhesion molecule-1, ICAM-1/CD54; vascular cell adhesion molecule-1, VCAM-1/CD106; and E-selectin, ELAM-1/CD62E) were detected on the surface of isolated CECs using immunofluorescence technique. Appearance of CECs with markers for endothelial cell activation, together with increased levels of TNF-α and VEGF and decreased levels of protein C and protein S in the circulation, may account for the propensity of vascular perturbation in thalassemic subjects. Am. J. Hematol. 70:100–106, 2002.