Neutrophil activation in sickle cell disease.

Vascular occlusion is the main cause of the morbidity and mortality observed in patients with sickle cell disease (SCD). Increasing evidence indicates that (activated) neutrophils could play an important role in the initiation and propagation of vaso-occlusive processes in SCD. In this study, the activation state of neutrophils in sickle cell patients was analyzed by determining the level of expression of neutrophil antigens such as CD62L, CD11b, CD66b, CD63, and Fcgamma receptors. We also analyzed plasma levels of lactoferrin, elastase, soluble (s)CD16 (sFcgammaRIII), and serum levels of soluble (s)CD62L (sL-selectin) as neutrophil activation markers in these patients. Significant differences were observed in the activation state of neutrophils in non-symptomatic sickle cell patients compared to healthy HbAA controls as exemplified by significant decrease in L-selectin expression, enhanced expression of CD64, and increased levels of soluble markers like sL-selectin, elastase, and sCD16. During vaso-occlusive crisis the differences were even more pronounced. These results show neutrophils to be activated in sickle cell patients, suggesting a role of importance in the pathophysiology of sickle cell disease.