Dendritic cells physiology

Drury AN, Szent-Gyorgyi A (1929) The physiological activity of adenine compounds with especial reference to their action upon the mammalian heart. J Physiol 68(3) 213—237 Englert M, Quitterer U, Klotz K-N (2002) Effector coupling of stably transfected human A3 adenosine receptors in CHO cells. Biochem Pharmacol 64(l) 69-73 Fossetta J, Jackson J, Deno G, Fan X, Du XK, Bober L, Soude-Bermejo A, de Bouteiller O, Caux C, Lunn C, Lundell D, Palmer RK (2003) Pharmacological analysis of calcium responses mediated by the human A, adenosine receptor in monocyte-derived dendritic cells and recombinant cells. Mol Pharmacol 63(2) 342-350... 

In vitro, MDC is chemotactic for a number of cell types including thymocytes (Cambell et al., 1999 Chantry et al., 1999), dendritic cells, monocytes, IL-2-activated NK cells (Godiska et al., 1997), TH2 T cells (Bonecchi et al., 1998 Sallusto et al., 1998 Imai et al, 1998) and CLA + Tcells (Cambell et al, 1999). MDC has also been reported to inhibit HIV replication in vitro (Pal et al, 1997 Struyf et al, 1999), although the physiological significance of this observation is still unclear. 

Such microvesicles have size variable between 50 nm to 1 (xm and differ from other vesicles (like exosomes (30-100 nm)). In general, microparticles are phospholipids vesicles derived from eukaryotic cells as a result of different types of stimulation. Microparticles can also be defined as phospholipids microvesicles containing certain membrane proteins originating from the parental cell. Microparticles circulate in the blood and contribute to numerous physiological processes. MPs have been described in various haematopoietic cells as platelets (Heijnen et al. 1999), T-cells (Blanchard et al. 2002), polynuclear neutrophils (Mesri and Altieri 1999) or dendritic cells. After have been considered as cell dust, MPs are now considered to reflect cell activation. Platelet derived microparticles have been the most extensively studied until now. They are now accepted to play an important role in the procoagulant... 

Immunomodulation not only relates to a series of physiologic and pathologic phenomena, but also it can be estimated by related reaction cells, such as mast cells, DCs and NK cells, and level of cell factors such as interleukin, interferon, tumor necrosis factor, and transforming growth factor. Based on those facts, the rat mast cell and rabbit aortic assay [105], dendritic cell assay [106], lymphoid organ assay [107], IFN-y assay [108], anti-rHuEPO NAb assay [109], and chemotaxic assay [110] are established. 

In the guinea pig TRPV1-positive nerve fibers are locahzed within the epithelium of the trachea and around smooth muscle and blood vessels and within the lower airways, in the vicinity of bronchi and bronchioles, and around alveolar tissue, whereas no TRPV 1 was found within airway epithelial cells (Watanabe et al. 2005). The physiological relevance of TRPVl mRNA expression, together with that of other ion channels in bronchial epithehal cells (Agopyan et al. 2003), remains questionable. Similarly, expression of TRPV 1 in dendritic cells (Basu and Srivastava, 2005) and the associated hypothesis that TRPV 1 orchestrates an early immune response has been challenged by failure to detect any functional TRPV 1 in these inflammatory cells (O Connell et al. 2005). We cannot exclude that in the airways, as in other tissues, TRPV 1 occurs in extraneuronal cells, from where it may contribute to homeostasis, inflammation, and ultimately the regulation of the tussive response. However, we underline that this hypothesis lacks conclusive experimental proof. 

With both pollens and fecal pellets, the focal concentration of total protein (allergens) eluted onto the mucosal surface may be in the order of milligrams per milliliter (15,17). As such, allergens released into the vicinity of cells within the respiratory tree are likely to be present in sufficient concentration to be physiologically or physicochemically potent. The relative importance and role of each cell type remains speculative but cells, such as epithelial cells, macrophages, mast cells, and dendritic cells, are obvious candidates and will be discussed in the following sections. 

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