RESUMO
The abnormal interaction between sickle cells and vascular endothelium may be of greater relevance for vaso-occlusive events than are alteration of red cell morphology or viscosity. One endothelial cell derived component extremely sensitive to cell injury is the vasoconstrictor peptide; endothelin-1 [ET-1] which has been found to be increased in patients with ischemic manifestations. Plasma ET-1 was assessed in this work to mirror endothelial cell interactions and to clarify its role in sickle cell anemia as a co-factor in the pathogenesis of vaso-occlusive events. According to their clinical presentation, patients were divided into two groups: Group I [n=18] were in steady state of sickle cell anemia, 12 of them [Group II] presented with acute painful crisis during the study period. Both groups were subjected to full clinical examination, routine hematological evaluation and measurement of plasma ET-1 level using ELISA technique. Our results were compared to a reference group of 15 age- and sex-matched normal controls. A statistically significant increase of levels of plasma ET-1 was demonstrated in patients during crisis compared to those during the steady state of their disease [p<0.05]. Similarly, ET-1 level was higher in both groups than the controls [p<0.05]. There was a significantly higher level of ET-1 in patients with hepatomegaly versus those without enlarged liver [p<0.05]. A significant negative correlation between ET-1 and frequency of blood transfusion was detected in this study, while a significant positive correlation between it and hemoglobin S was also found. However, no correlation was present between ET-1 and frequency of previous vaso-occlusive crises. ET-1 could contribute to both the prolonged vasospasm and inflammation mediating painful crisis in sickle cell anemia. Endothelin antagonist strategies might have good utility in the treatment of this complex clinical disorder