<P> Firstly, at the site of infection histamine release causes vasodilation of the capillaries near the injured area which slows down the blood flow in the region and encourages leukocytes, such as neutrophils, to come closer to the endothelium, and away from the centre of the lumen where the rate of blood flow is highest . Once this occurs weak interactions are made between the selectins expressed on the neutrophil and endothelial cells (expression of which is also increased through the action of CXCL8 and other cytokines). On the neutrophil these are: L selectins, and on the endothelial cell: P and E selectins . This causes the "rolling" phase of chemotaxis . </P> <P> Once the neutrophil is rolling along the endothelium, it will come into contact with a CXCL8 molecule expressed on the surface which stimulates the cell signalling pathway, mediated through a G - coupled - protein - receptor . The binding of CXCL8 to CXCR1 / 2 on the neutrophil stimulates the neutrophils to upregulate their expression of the integrin, LFA - 1, which takes part in high affinity bonding with ICAM - 1 receptors expressed on the endothelium . The expression and affinity of LFA - 1 is significantly increased to maximise binding . This causes the neutrophil to slow down more until it is stationary . Another key function of the cell signalling stimulated by CXCL8, is the initiation of the oxidative burst . This process allows the build up of proteolytic enzymes and reactive oxygen species (ROS) which are necessary to break down the ECM and basement membrane . These are released in secretory granules, along with more integrins . The release of ROS and damaging enzymes is regulated to minimise host damage, but continues to reach site of infection at which it will carry out its effector functions . </P> <P> While neutrophil granulocytes are the primary target cells of IL - 8, there are a relatively wide range of cells (endothelial cells, macrophages, mast cells, and keratinocytes) that respond to this chemokine . The chemoattractant activity of IL - 8 in similar concentrations to vertebrates was proven in Tetrahymena pyriformis, which suggests a phylogenetically well - conserved structure and function for this chemokine . </P> <P> Interleukin - 8 is a key mediator associated with inflammation where it plays a key role in neutrophil recruitment and neutrophil degranulation . As an example, it has been cited as a proinflammatory mediator in gingivitis and psoriasis . </P>

Cells attracted to the site of infection by il-8 are