Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The anaphylactic function of IgE has been intensively investigated. The Fc epsilon receptor on mast cells or basophils combines with the last two constant domains of the epsilon heavy chain. The Fc epsilon receptor is apparently a glycoprotein, monovalent and free in the plasma membrane. The interaction between the antigen (allergen) and the corresponding IgE antibody combined with the Fc epsilon receptor results in the aggregation of the receptors. Receptor dimerization suffices to trigger the cell. Compartments can be described in mast cells or basophils, the activity of which depends upon the number of formed receptor dimers on the corresponding membrane area. Beyond a threshold number of dimerized receptors, the cell compartment is triggered, which in the presence of Ca++ leads to the discharge of mast cell mediators, an increasing function of the dimer number. Excess receptor aggregation or the absence of aggregation (i.e. IgE-Ag2 complexes) deactivates the cell, which occurs more often in the absence of Ca++. Thus, IgE molecules play a passive role only in allowing the aggregation of the receptors which delivers the activating signal. But through the composition of IgE-antigen complexes bound to the receptors, IgE also modulates the cell function according two antagonistic reactions in permanent balance, i.e. activation or deactivation. IgE molecules are also involved in immediate type reactions in inducing the release of lysosomal enzymes from mononuclear phagocytes. But IgE antibody can also, when complexed with the antigen, trigger macrophage cytotoxicity for the corresponding target, which indicates a new function of IgE in the effector mechanisms of immunity of particular importance in immunity to schistosomes. A receptor for aggregated IgE has been characterized on the membrane of macrophages. The binding of IgE to its macrophage receptor triggers the cell, as shown by the resulting increase in cyclic GMP, calcium uptake and accelerated turn-over of lysosomal enzymes. A receptor for IgE has also been described on lymphoid cells, B cells, null cells and recently T cells, and the appearance of the receptor is modulated by IgE molecules themselves, suggesting a homeostatic role of IgE molecules. IgE appears thus to play various functions, the most dramatic being the triggering of anaphylactic reactions. But the role of IgE in activating mononuclear phagocytes or lymphoid cells might also prove to be of importance in immunity.
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PMID:[Cellular interactions of IgE: towards a new function for IgE]. 700 8

Inhalation of crystalline silica results in pulmonary fibrosis and silicosis. It has been suggested that mast cells play a role in these conditions. How mast cells would influence pathology is unknown. We thus explored mast cell interactions with silica in vitro and in B6.Cg-kit(W-sh) mast cell-deficient mice. B6.Cg-kit(W-sh) mice did not develop inflammation or significant collagen deposition after instillation of silica, while C57Bl/6 wild-type mice did have these findings. Given this supporting evidence of a role for mast cells in the development of silicosis, we examined the ability of silica to activate mouse bone marrow-derived mast cells (BMMC), including degranulation (beta-hexosaminidase release); production of reactive oxygen species (ROS) and inflammatory mediators; and the effects of silica on Fc epsilon RI-dependent activation. Silica did not induce mast cell degranulation. However, TNF-alpha, IL-13, monocyte chemotactic protein-1, protease activity, and production of ROS were dose-dependently increased after silica exposure, and production was enhanced after Fc epsilon RI stimulation. This mast cell activation was inhibited by anti-inflammatory compounds. As silica mediates some effects in macrophages through scavenger receptors (SRs), we first determined that mast cells express scavenger receptors; then explored the involvement of SR-A and macrophage receptor with colleagenous structure (MARCO). Silica-induced ROS formation, apoptosis, and TNF-alpha production were reduced in BMMC obtained from SR-A, MARCO, and SR-A/MARCO knockout mice. These findings demonstrate that silica directs mast cell production of inflammatory mediators, in part through SRs, providing insight into critical events in the pathogenesis and potential therapeutic targets in silicosis.
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PMID:Silica-directed mast cell activation is enhanced by scavenger receptors. 1690 92