The Leukocyte adhesion cascade is a process through which leukocytes (white blood cells) leave blood vessels and enter injured tissue. This process results in inflammation. The five steps of the leukocyte adhesion cascade are: White Blood Cells is also the name of a White Stripes album. ... The arterial system The blood vessels are part of the circulatory system and function to transport blood throughout the body. ...

1. capture (or transitory adhesion);
2. rolling;
3. slow rolling;
4. firm adhesion; and,
5. transmigration across the endothelium.

When cellular damage (trauma) occurs, the cells express (emit) P-selectin and secrete chemokines (for more information, please refer to Eukaryotic chemotaxis). Leukocytes naturally express the related molecule L-selectin. Selectin molecules have many surface receptors which are required for adhesive bonding. Leukocytes in the vicinity of damaged tissue are attracted by the presence of the chemokines. When the leukocyte gets close enough, the capture process initiates, and the leukocyte briefly adheres to the venular endothelium (inner cellular lining of veins). The leukocyte then rolls across the surface of the venular endothelium at a high rate of speed (though slower than cells moving freely in the bloodstream). Rolling occurs when the selectin molecules bond to one another in the direction of the roll, but break bonds in the trailing direction. The speed of rolling may decrease (alternately, the leukocyte may break free), particularly in the case where E-selectin is expressed in the region. Eventually, a slow-rolling leukocyte will firmly adhere to the lining of the vein, as the selectin molecule receptors bond. The leukocyte will then travel through the cellular wall, following the chemokines trail to the source of the chemoattractants. Rolling is a process in physiology where a white blood cell connects with endothelium cells via complementary surface adhesion molecules (selectins), rolling along it like a tumbleweed. ... Transmigration can has several meanings: Transmigration of the soul is a common term for reincarnation. ... The endothelium is the layer of thin, flat cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. ... P-selectin is a cell adhesion molecule (CAM) found in granules in endothelial cells (cells lining blood vessels) and activated platelets. ... Chemokines are a class of chemotactic cytokines, or small secreted protein signals. ... Chemotaxis is the phenomenon in which bodily cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. ... Selectins are a family of cell-surface adhesion molecules of leukocytes and endothelial cells. ... Receptor may refer to: In telecommunication, a receiver. ...

In an inflammatory response, leukocytes collectively are in every step of the cascade. Individually, they are in one step or another. It has been demonstrated that leukocyte recruitment is halted whenever any of the five steps is suppressed. It should be noted that supressed expression of some selectin types (particularly L-selectin) will result in slower immune response. Normal immune response occurs in fewer than ten minutes. If L-selectin is not produced, the immune system response may be ten times slower, as P-selectin to P-selectin bonding occurs (leukocytes can also produce P-selectin). P-selectin to P-selectin bonds are equally strong, but occur less frequently because the receptor site density is lower than with the smaller E-selectin molecules; the resulting increase in initial rolling speed causes the slow rolling phase -- which ultimately allows firm adhesion and transmigration -- to take a longer period of time. Inflammation is the first response of the immune system to infection or irritation and may be referred to as the innate cascade. ...

References

• Leukocyte adhesion cascade