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Mechanism of the antigen-independent cytokinergic SPE-7 IgE activation of human mast cells in vitro.

ABSTRACT: Release of pro-inflammatory mediators by mast cells is a key feature of allergic disease. The 'dogma' is that IgE molecules merely sensitise mast cells by binding Fc?RI prior to cross-linking by multivalent allergen, receptor aggregation and mast cell activation. However, certain monoclonal IgE antibodies have been shown to elicit mast cell activation in an antigen-independent cytokinergic manner, and DNP-specific murine SPE-7 IgE is the most highly cytokinergic antibody known. We show that both monovalent hapten and recombinant SPE-7 IgE Fab inhibit its cytokinergic activity as measured by mast cell degranulation and TNF-? release. Using SPE-7 IgE, a non-cytokinergic human IgE and a poorly cytokinergic murine IgE, we reveal that interaction of the Fab region of 'free' SPE-7 IgE with the Fab of Fc?RI-bound SPE-7 IgE is the basis of its cytokinergic activity. We rule out involvement of IgE Fc, C?1 and C?/? domains, and propose that 'free' SPE-7 IgE binds to Fc?RI-bound SPE-7 IgE by an Fv-Fv interaction. Initial formation of a tri-molecular complex (one 'free' IgE molecule cross-linking two receptor-bound IgE molecules) leads to capture of further 'free' and receptor-bound IgEs to form larger clusters that trigger mast cell activation.

SUBMITTER: Bax HJ

PROVIDER: S-EPMC4402612 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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Mechanism of the antigen-independent cytokinergic SPE-7 IgE activation of human mast cells in vitro.

Bax Heather J HJ Bowen Holly H Dodev Tihomir S TS Sutton Brian J BJ Gould Hannah J HJ

Scientific reports 20150420

Release of pro-inflammatory mediators by mast cells is a key feature of allergic disease. The 'dogma' is that IgE molecules merely sensitise mast cells by binding FcεRI prior to cross-linking by multivalent allergen, receptor aggregation and mast cell activation. However, certain monoclonal IgE antibodies have been shown to elicit mast cell activation in an antigen-independent cytokinergic manner, and DNP-specific murine SPE-7 IgE is the most highly cytokinergic antibody known. We show that both ...[more]

PMID: 25892150

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Project description:Mast cells (MCs) are granular cells of the innate immune system which develop from CD34+/CD117+ progenitors and play a role in orchestrating adaptive immune responses. They have a well-known role in allergic reactions following immunoglobulin (Ig)E-mediated activation of the cell-surface expressed IgE high-affinity receptor (Fc?RI). MCs can also respond to various other stimuli due to the expression of a variety of receptors including toll-like receptors (TLRs), immunoglobulin (IgG) receptors (Fc?R), complement receptors such as C5a (CD88) expressed by skin MCs, neuropeptides receptors including nerve growth factor receptor, (NGFR), cytokines receptors such as (IL)-1R and IL-3R, and chemokines receptors including CCR-1 and CCR-3. MCs release three groups of mediators upon degranulation differentiated according to their chemical composition, storage, and time to release. These include preformed mediators (mainly histamine, tryptase, and chymase), de novo synthesized mediators such as prostaglandin (PG)D2, leukotriene (LT)B4 and LTD4, and cytokines including IL-1?, IL-3, tumor necrosis factor (TNF)?, and transforming growth factor(TGF)-?. Emerging evidence indicates a role for IgE-independent MC activation in the late-stage asthmatic response as well as in non-allergic airway diseases including chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and lung cancer. MC infiltration/activation has been reported in some, but not all, studies of lung cancer. MC-derived TNF-? possesses tumor-suppressive activity while IL-1? supports tumor progression and metastasis. In IPF lungs, an increase in density of tryptase- and chymase-positive MCs (MCTC) and overexpression of TGF-? support the fibrosis progression. MC-derived chymase activates latent TGF-? that induces the differentiation of fibroblasts to matrix-producing myofibroblasts. In summary, increasing evidence highlights a critical role of MCs in non-allergic diseases that may indicate new approaches for therapy.

Dataset Information

Mechanism of the antigen-independent cytokinergic SPE-7 IgE activation of human mast cells in vitro.

Publications

Mechanism of the antigen-independent cytokinergic SPE-7 IgE activation of human mast cells in vitro.

Similar Datasets

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