http://en.wikipedia.org/wiki/Phagocyte
When an infection occurs, a chemical "SOS" signal is given off to attract phagocytes to the site.These chemical signals may include proteins from invading bacteria, clotting system peptides, complement products, and cytokines that have been given off by macrophages located in the tissue near the infection site.Another group of chemical attractants are cytokines that recruit neutrophils and monocytes from the blood.
To reach the site of infection, phagocytes leave the bloodstream and enter the affected tissues. Signals from the infection cause the endothelial cells that line the blood vessels to make a protein called selectin, which neutrophils stick to on passing by. Other signals called vasodilators loosen the junctions connecting endothelial cells, allowing the phagocytes to pass through the wall. Chemotaxis is the process by which phagocytes follow the cytokine "scent" to the infected spot. Neutrophils travel across epithelial cell-lined organs to sites of infection, and although this is an important component of fighting infection, the migration itself can result in disease-like symptoms.During an infection, millions of neutrophils are recruited from the blood, but they die after a few days.
When an infection occurs, a chemical "SOS" signal is given off to attract phagocytes to the site.These chemical signals may include proteins from invading bacteria, clotting system peptides, complement products, and cytokines that have been given off by macrophages located in the tissue near the infection site.Another group of chemical attractants are cytokines that recruit neutrophils and monocytes from the blood.
To reach the site of infection, phagocytes leave the bloodstream and enter the affected tissues. Signals from the infection cause the endothelial cells that line the blood vessels to make a protein called selectin, which neutrophils stick to on passing by. Other signals called vasodilators loosen the junctions connecting endothelial cells, allowing the phagocytes to pass through the wall. Chemotaxis is the process by which phagocytes follow the cytokine "scent" to the infected spot. Neutrophils travel across epithelial cell-lined organs to sites of infection, and although this is an important component of fighting infection, the migration itself can result in disease-like symptoms.During an infection, millions of neutrophils are recruited from the blood, but they die after a few days.
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