Fig. 1.

The life of a neutrophil. Neutrophils are generated through granulopoiesis in the bone marrow. They are released into the blood circulation through decreased CXCR4-CXCL12 signaling. Upon injury/infection/hypoxia in tissue, the endothelium will signal to induce the leukocyte recruitment cascade involving rolling, adhesion, crawling, and extravasation. Neutrophils can be recruited to a range of different tissue needs such as infection, sterile injury, and hypoxia. A recently discovered feature of the neutrophil is the ability to leave an injured site to reverse transmigrate into the blood stream to further age and home to the bone marrow to be cleared, also in a CXCR4-CXCL12-dependent manner. HSC hematopoietic stem cell, CXCR CXC chemokine receptors, PSGL-1 P-selectin glycoprotein ligand-1, LFA-1 - lymphocyte function-associated antigen-1, VLA-4 very late antigen-4, Mac-1 macrophage-1 antigen, DAMPs damage-associated molecular patterns, PAMPs pathogen-associated molecular patterns, VEGF-A vascular endothelial growth factor-A, VEGFR1 vascular endothelial growth factor receptor-1, MMP-9 matrix metalloproteinase-9