**4. Process of neutrophil cells penetration to the tissues**

Migration of neutrophil cells from blood circulation into the surrounding tissues, this process consider as the key role that trigger host defense. Neutrophil transmigration across the vascular endothelium is a highly regulated process that requires the up-regulation of neutro‐ phil and endothelial cell (EC) adhesion molecules. During neutrophil adhesion to ECs, binding of the neutrophil or EC adhesion molecules to their ligands may induce intracellular signaling pathways and downstream events, which may in turn modulate neutrophil transmigration. Indeed, the ligation of various adhesion molecules can initiate signal transduction pathways and induce subsequent cellular changes [11].
