Increased levels of soluble P-selectin correlate with iron overload in sickle cell disease

Homozygous sickle cell disease (SCD) is characterised by increased soluble P-selectin (sP-selectin), suggesting increased platelet activation, and high non-transferrin-bound iron (NTBI), reflecting iron overload, possibly due to blood transfusion. Hypothesising a relationship between these processes, we measured both markers in 40 SCD patients and 40 age/gender/race-matched controls, finding increased levels of each marker in the patients (both P<0.001), but more pertinently a significant NTBI/sP-selectin correlation (r=0.52, P<0.001). Both indices were increased in the blood of 15 recently-transfused patients compared with 25 three-month transfusion-free patients (P<0.001), but only sP-selectin was higher in present sickle crisis (P<0.001). We suggest that increased NTBI associated with blood transfusion iron overload in SCD may promote platelet activation.