Soluble P-selectin and vascular endothelial growth factor in steady state sickle cell disease: relationship to genotype

Sickle cell disease (SCD) is characterised by abnormal coagulopathy and angiogenesis although their relationships in two common genotypes, homozygous (HbSS) SCD and sickle-haemoglobin C disease (HbSC), are unexplored. We measured markers of platelet activation (soluble P-selectin [sP-selectin]), fibrinolysis (D-dimer) and angiogenesis (vascular endothelial growth factor [VEGF]) in 27 HbSS patients, 37 HbSC patients and in 42 age and race matched subjects with normal haemoglobin (AA). sP-selectin (P = 0.025) and D-dimers (P <0.001) were higher in HbSS than in HbSC but there was no difference in VEGF. In HbSC, sPselectin correlated with VEGF (P = 0.012) and D-dimers (P = 0.021). There were no significant correlations in health or in HbSS. Platelet and coagulation activation, but not angiogenic activity, is elevated in HbSS disease compared to the clinically milder HbSC genotype. The correlation between sP-selectin and VEGF in SCD and HbSC disease is consistent with the view that VEGF is released from platelets during in vivo activation.