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High Affinity IgE Receptor (high + affinity_ige_receptor)
Selected AbstractsPoint mutations of 3BP2 identified in human-inherited disease cherubism result in the loss of functionGENES TO CELLS, Issue 11 2004S. M. Shahjahan Miah Adaptor protein 3BP2 positively regulates the high affinity IgE receptor (Fc,RI)-mediated activation of degranulation in mast cells. Genetic study identified the point mutations of 3BP2 gene in human-inherited disease cherubism. The multiple cysts in cherubism lesion of jaw bones are filled with the activated osteoclasts and stromal cells, including mast cells. By over-expression study using rat basophilic leukaemia RBL-2H3 mast cells, we have analysed the effect of the point mutations on the function of 3BP2 protein, which plays a positive regulatory role on Fc,RI-mediated mast cell activation. Over-expression of 3BP2 mutants suppressed the antigen-induced degranulation and cytokine gene transcription. Antigen-induced phosphorylation of Vav1, activation of Rac1, extracellular signal regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38 mitogen activated protein kinase (MAPK), inhibitor of nuclear factor ,B kinase (IKK) and nuclear factor of activated T cells (NFAT) were all impaired in the cells over-expressing the cherubism mutants of 3BP2. Furthermore, cherubism mutations of 3BP2 may abrogate the binding ability to interact with chaperone protein 14-3-3. These results demonstrate that over-expression of the mutant form of 3BP2 inhibits the antigen-induced mast cell activation. It suggests that point mutations of 3BP2 gene cause the dysfunction of 3BP2 in vivo. [source] Counter regulation of the high affinity IgE receptor, Fc,RI, on human airway dendritic cells by IL-4 and IL-10ALLERGY, Issue 11 2009A. Faith Background:, Immunoglobulin E is a signalling molecule within the environment of the respiratory tract, the high affinity receptor for which, Fc,RI, is expressed by dendritic cells (DC). Little is known, however, of the expression and function of Fc,RI on DC in the human respiratory tract. Methods:, CD1c+ DC were purified from surgically resected nasal turbinates of 11 atopic and 12 nonatopic patients with chronic rhinosinusitis. Expression of Fc,RI was determined by flow cytometry. Cytokine production by DC was determined by cytometric bead array. Results:, Expression of Fc,RI was significantly elevated on respiratory tract dendritic cells (RTDC) from atopic as compared to nonatopic patients. Activation of RTDC through Fc,RI induced production of the pro-inflammatory cytokines IL-6 and TNF-,, and the anti-inflammatory cytokine IL-10. The production of IL-6 and TNF-, was elevated in atopic compared to nonatopic patients studied. Conversely IL-10 production was elevated in nonatopic patients. Concomitant activation of Fc,RI and stimulation of RTDC with IL-4 inhibited production of IL-10 by RTDC. Neutralization experiments with anti-IL-10 Ab enhanced whereas addition of exogenous IL-10 to RTDC inhibited Fc,RI-mediated inflammatory cytokine production. Conclusion:, The function of Fc,RI on RTDC from patients with rhinosinusitis is susceptible to counter regulation by IL-4 and IL-10. [source] EAACI/GA2LEN task force consensus report: the autologous serum skin test in urticariaALLERGY, Issue 9 2009G. N. Konstantinou Injection of autologous serum collected during disease activity from some patients with chronic spontaneous urticaria (CU) into clinically normal skin elicits an immediate weal and flare response. This observation provides a convincing demonstration of a circulating factor or factors that may be relevant to the understanding of the pathogenesis and management of the disease. This test has become known as the autologous serum skin test (ASST) and is now widely practised despite incomplete agreement about its value and meaning, the methodology and the definition of a positive response. It should be regarded as a test for autoreactivity rather than a specific test for autoimmune urticaria. It has only moderate specificity as a marker for functional autoantibodies against IgE or the high affinity IgE receptor (Fc,RI), detected by the basophil histamine release assay, but high negative predictive value for CU patients without them. It is usually negative in other patterns of CU, including those that are physically induced. Positive ASSTs have been reported in some subjects without CU, including those with multiple drug intolerance, patients with respiratory allergy and healthy controls, although the clinical implications of this are uncertain. It is essential that failsafe precautions are taken to ensure that the patient's own serum is used for skin testing and aseptic procedures are followed for sample preparation and handling. CU patients with a positive ASST (ASST+) are more likely to be associated with HLADR4, to have autoimmune thyroid disease, a more prolonged disease course and may be less responsive to H1-antihistamine treatment than those with a negative ASST (ASST,) although more evidence is needed to confirm these observations conclusively. [source] The mast cell and allergic diseases: role in pathogenesis and implications for therapyCLINICAL & EXPERIMENTAL ALLERGY, Issue 1 2008J. M. Brown Summary Mast cells have long been recognized for their role in the genesis of allergic inflammation; and more recently for their participation in innate and acquired immune responses. Mast cells reside within tissues including the skin and mucosal membranes, which interface with the external environment; as well as being found within vascularized tissues next to nerves, blood vessels and glandular structures. Mast cells have the capability of reacting both within minutes and over hours to specific stimuli, with local and systemic effects. Mast cells express the high affinity IgE receptor (Fc,RI) and upon aggregation of Fc,RI by allergen-specific IgE, mast cells release and generate biologically active preformed and newly synthesized mediators which are involved in many aspects of allergic inflammation. While mast cells have been well documented to be essential for acute allergic reactions, more recently the importance of mast cells in reacting through pattern recognition receptors in innate immune responses has become recognized. Moreover, as our molecular understanding of the mast cell has evolved, novel targets for modulation have been identified with promising therapeutic potential. [source] Genetic variation in the beta subunit of the high affinity IgE receptor and atopy and asthmaCLINICAL & EXPERIMENTAL ALLERGY, Issue 7 2006Julian Hopkin No abstract is available for this article. [source] Leukotrienes and other mast cell mediators cause asthmatic airway obstructionCLINICAL & EXPERIMENTAL ALLERGY REVIEWS, Issue 2004S.-E. Dahlén Summary From an evolutionary perspective, bronchoconstriction is a highly conserved mechanism for defence against stimuli that are noxious for the lung and airways. The presence of mast cells in all layers of the airways makes them ideally situated to function as sensors of environmental changes that require such a host defence reaction. In addition to being activated by high affinity IgE receptors, many other trigger factors are known to activate signal transduction pathways leading to mast cell degranulation. This includes changes in the physical and chemical composition of the environment, exposure to endotoxin and other microbial factors acting on Toll-like receptors [1], intake of certain drugs and in particular virtually all nonsteroidal anti-inflammatory drugs (NSAIDs) in subjects with the peculiar syndrome aspirin-intolerant asthma (AIA) [2]. Irrespective of the trigger, the consequence of mast cell activation is release of biologically active smooth muscle stimulating mediators as well as the secretion of cytokines, chemotactic factors and enzymes that are believed to trigger further cascades contributing to long-term tissue remodelling and chronic airway inflammation. [source] | ||||||||||