Leukocyte motility

Mechanism of Action An alkaloid that decreases leukocyte motility, phagocytosis, and lactic acid production. Therapeutic Effect Decreases urate crystal deposits and reduces inflammatory process. 

Measurement of leukocyte motility and che-motaxis parameters using a quantitative analysis of the under-agarose migration assay (with D. Lauffenburger). Math. BioscL 44, 121-138 (1978). 

MOA Inhibit prostaglandin synthesis by decreasing activity of cyclo-oxygenase Decreases the deposition of urate crystals in joints by decreasing leukocyte motility Decreases the motility of PMN leukocytes Competitive inhibition of uric acid reabsorption at the proximal tubule Inhibits xanthine oxidase, thus preventing uric acid production... 

Decreases leukocyte motility, phagocytosis, lactic acid production, resulting in decreased urate crystal deposits, inflammatory process... 

Lauffenburger, D., C. Rothman, and S. Zigmond, Measurement of leukocyte motility and chemotaxis parameters with a linear under-agarose migration assay. Journal of Immunology, 1983, 131, 940-947. 

The precise mechanism of action of this drug is not yet known, although it is believed to minimize appreciably leukocyte motility, phagocytosis, and also lactic acid production, thereby lowering the deposition of urate crystals and the inflammatory response. In fact, all these effects combinedly relate to the interference of colchicine upon the cellular mitotic spindles progressively. 

For statistical analysis of leukocyte motility, capture enough movies (minimum of N = 3 per treatment) such that 20-30 leukocytes can be accurately tracked for each treatment. We often use the track point function of MetaMorph to track cells. 

Buettner, H.M., Lauffenburger, D.A., and ZSgmond, S.H. (1989). Measurement of leukocyte motility and chemotaxis parameters with the MiUipore filter assay. /. Immunol. Meth. 123, 25-37. 

Leukocyte motility is dependent upon the activity of the hexose monophosphate shunt, which in turn is activated by ascorbate (84, 94, 173) oxidizing NADPH to NADP with release of bacteriocidal peroxide (252). A review of oxygen-dependent phagocytosis has recently been published (9). 

Lacalle RA, Gomez-Mouton C, Barber DF, et al. PTEN regulates motility but not directionality during leukocyte chemotaxis. J Cell Sci 2004 117(Pt 25) 6207-6215. 

Colchicine, an alkaloid obtained from the autumn crocus, has long been used and is relatively selective for the treatment of acute gouty arthritis. Unlike many of the newer agents for use in gout, colchicine has minimal effects on uric acid synthesis and excretion it decreases inflammation associated with this disorder. It is thought that colchicine somehow prevents the release of the chemotactic factors and/or inflammatory cytokines from the neutrophils, and this in turn decreases the attraction of more neutrophils into the affected area (Fig. 37.1).The ability of colchicine to bind to leukocyte microtubules in a reversible covalent complex and cause their depolymerization also may be a factor in decreasing the attraction of the motile leukocytes into the inflamed area. 

While confirming the general normality of the mutant mice and problems with lymphocyte homeostasis, these studies focused on identifying defects in peripheral leukocytes. The Lsc- - mice had a twofold increase in circulating neutrophils and lymphocytes but normal platelet counts and red blood cells. In functional studies, the Lsc-/ neutrophils showed a reduced ability to stimulate formation of Rho-GTP and abnormal pseudopod development in response to fMLP. An increased motility and lower adherence of the neutrophils when stimulated with fMLP (Francis et ah, 2006) are similar to the behavior of B cells from Lsc / mice when stimulated with serum (Girkontaite et ah, 2001). While these studies imply a role for a G12/i3 Lsc-RhoA pathway in the phenotypes of these cells, the molecular details are not yet known. 

Various types of immunodepressant effects of local anesthetics can be detected by laboratory testing, although they may have no clinical significance. Lidocaine dose-dependently inhibits EA rosetting by human lymphocytes. In vitro depression of human leukocyte random motility and phagocytosis has also been reported (SED-11, 220) (41). 

These external neural influences on intestinal motility are common targets for prokinetic drugs, but events within the bowel can have important effects on intestinal motility and cause the bowel to be refractory to traditional prokinetic therapy. Release of cytokines from activated inflammatory cells is probably an important feature of ileus in many cases. Ileus secondary to reperfusion injury is an anticipated response in horses with small intestinal obstruction. However, even apparently mild intestinal injury can initiate cellular responses that lead to impaired motility. Mild intestinal insult by gentle surgical manipulation activated adhesion molecules on leukocytes and increased the expression of P-selectin and intercellular adhesion molecule 1 on endothelial cells within the vasculature of the muscularis layer of the intestine (Kalff et al 1999). Surgical manipulation of the rodent small intestine resulted in substantial extravasation of leukocytes into the intestinal muscularis, consisting mainly of polymorphonuclear neutrophils, monocytes and mast cells and lasting for days. This cellular inflammatory response within the intestinal muscularis externa was associated with a marked decrease in jejunal circular muscle activity (Kalff et al 1998). 

Neutrophils arc the primary innate defense against pathogenic bacteria. They make up most (SO to 75(3>) of the leukocyte fraction in the bhxid. Micro.scopically. neutrophils have mullilobcd nuclei. They respond to chemical motility factors such as complement mediators released from infected i>r inflamed tissues and migrate to a site of infection by the process of chemotaxis. There, they recognize, adhere to, and phagocytose invading microbes. 

The Boyden chamber is a simple apparatus used to test for chemotaxis, especially of leukocytes. It can also be used to assess tumor cell transmigration across an endo-thehal monolayer in vitro. It consists of two compartments separated by a MiUi-pore filter (3-8 pm pore size). A chemotac-tic factor is placed in one compartment, and a gradient develops across the thickness of the filter (ca. 150 pm). Cell movement into the filter is measured after an incubation period less than the time taken for the gradient to decay. Cell motility can be measured in Boyden chambers containing filters precoated with different materials, for example fibronectin or fibronectin fragments. The method, when apphed to malignant and non-mahgnant cell hnes, shows that the variable invasive potentials of these cells correlate with their abihty to disrupt the endothelial cell monolayer. 

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