 The clinical course of sickle cell disease SCD is very variable. Some patients experience vaso-occlusive disease infrequently, but other patients develop the complication recurrently. The reason for the difference remains unclear. Although erythrocyte sickling occurs due to factors such as dehydration, infections, extreme of temperatures, acidosis, and hypoxia, neutrophil adhesion and activation are crucial in eliciting the vaso-occlusive crisis in patients with SCD. Activated neutrophils upregulate the expression of various cellular adhesion molecules that increase their stickiness in vivo. A murine model of SCD demonstrated the importance of the intestinal microbiome in influencing the kinetics of ageing neutrophils. Depletion of the microbiota with prolonged courses of broad-spectrum systemic antibiotics resulted in a reduction of the number of these neutrophils and protection against LPS-induced fatal vaso-occlusive crisis in these mice. 