Leukocyte movement

Chemokines—cytokines that regulate leukocyte movement... 

Simple formyjgmethionyl peptjge stimulate leukocyte movement and are chemotactic. Becker et al have synthesized a series of di-, tri-, and tetrapeptides, most of them being formyl methionyl peptides. These are chemotactic, stimulate phagocytosis of latex particles, and cause the selective release of lysosomal enzymes from PMN in the presence of cyto-chalasin B. There is a high degree of correlation between the ability of the peptides to enhance PMN movement and cause selective release of acid hydrolases. The presence of the formyl group on the methionine leads to a 3,000- to 30,000-fold increase in chemotactic activity. Further studies... 

The differentiation between chemokinesis (increase of spontaneous movement) and chemotaxis (increase of directed movement) might also be of importance [274], Thus, dibutyryl cyclic adenosine 3, 5 -monophosphate produces divergent effects upon the two parameters of leukocyte locomotion under certain conditions [275] consequently it would seem that leukocyte movement should include measurements of both chemokinesis and chemotaxis. It is also noteworthy that too large a... 

Human bodies are constantly exposed to a plethora of bacteria, viruses, and other inflammatory substances. To combat these infections and toxic agents, the body has developed a carefully regulated inflammatory response system. Part of that response is the orderly migration of leukocytes to sites of inflammation. Leukocytes literally roll along the vascular wall and into the tissue site of inflammation. This rolling movement is mediated by reversible adhesive interactions between the leukocytes and the vascular surface. 

By regulating the movement of different subsets of leukocytes from the peripheral blood to extravascular sites such as organs, skin, or connective tissue,... 

The cytochalasins are a group of metabolites produced by certain fungi (e.g., Helminthosporium dermatoideum) that inhibit actin-dependent types of cell movement such as leukocyte locomotion, phagocytosis, cytokinesis, the retraction of... 

Keller, H.U., Cottier, H. (1981). Crawling-like movements and polarization in non-adherent leukocytes. Cell Biol. Int. Rep. 5, 3-7. 

Schmalsteig, F.C, Rudloff, H.E., Hillman, G.R., Anderson, D.C. (1986). Two-dimensional and three-dimensional movement of human polymorphonuclear leukocytes Two fundamentally different mechanisms of locomotion. J. Leukocyte Biol. 40,677-691. 

Evans, J.F., Leblanc, Y., Fitzsimmons, B.J., Charleson, S.M., Nathaniel, D. and Leveille, C. (1987). Activation ofleuko-cy te movement and displacement of [ H]-leukotriene B4 from leukocyte membrane preparations by (12 - and (12S)-hydroxyeicosate-traenoic acid. Biochem. Biophys. Acta 917, 406-410. 

Also required by the immune response are the numerous chemokines. Chemoattractant molecules provide concentration gradients that direct the movement of B and T cells and other leukocytes.216 219 Chemokines bind to seven-helix receptors, often... 

An important aspect of the epithelium is an elaborate system of channels between the cells. These intercellular channels are capable of changing width as the hormone levels change during the menstrual cycle. The channels can accommodate rapid movement of leukocytes and large proteins such as IgG and albumin they are an important pathway of watery secretion from the blood network to the tissue. 

Recruitment of leukocytes is receptor-mediated. The products of inflammation, such as histamine, promote the immediate expression of P-selectin on endothelial cell surfaces. This receptor binds weakly to carbohydrate ligands on leukocyte surfaces and causes them to roll along the endothelial surface as bonds are made and broken. Cytokines from injured cells induce the expression of E-selectin on endothelial cells, which functions similarly to P-selectin. Cytokines also induce the expression of integrin ligands on endothelial cells, which further slow the movement of leukocytes. These weakly bound leukocytes are free to detach if not activated by chemokines produced in injured tissue. Activation increases the affinity of bound integrin receptors for ligands on the endothelial cell surface, firmly binding the leukocytes to the endothelium. 

Movement of leukocytes within the tissue occurs via chemotaxis. Leukocytes reaching the tissue interstitium bind to extracellular matrix proteins via expressed integrins and CD44 to... 

Leukocyte extravasation (movement of leukocytes out of the circulatory system)... 

---