HP and sickle cell disease: This suggests that scavenging Hb may prevent the formation of oxidized LDL (oxLDL); this theory is supported by a recent study showing that in sickle cell disease patients, the absence of Hp is associated with increased lipid peroxidation and oxidized LDL deposition in the pulmonary artery [32], suggesting the key role of Hp to prevent free Hb-catalyzed extensive LDL oxidation (Figure 1).