Intravenous immune globulin prevents venular vaso-occlusion in sickle cell mice by inhibiting leukocyte adhesion and the interactions between sickle erythrocytes and adherent leukocytes

Sickle cell vaso-occlusion is a complex multistep process likely involving heterotypic interactions among sickle erythrocytes (red blood cells [RBCs]), leukocytes (white blood cells [WBCs]), and endothelial cells. Recent data using intravital microscopy in a sickle cell mouse model suggest that adherent leukocytes in postcapillary venules play a critical role in vaso-occlusion by capturing circulating sickle RBCs. In the course of studies to investigate the adhesion receptors mediating sickle RBC-WBC interactions, we found that control nonspecific immunoglobulin G (IgG) preparations displayed significant inhibitory activity. As a result, we studied the effects of commercial intravenous human immune globulin (IVIG) preparations and found that IVIG inhibits RBC-WBC interactions in cremasteric venules in a dose-dependent manner. IVIG of at least 200 mg/kg dramatically reduced these interactions, even after tumor necrosis factor-α (TNF-α) stimulation, and not only increased microcirculatory blood flow but also improved survival of sickle cell mice. These data raise the possibility that IVIG may have a beneficial effect on sickle cell-associated vaso-occlusion.