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  • 1
    ISSN: 1420-908X
    Keywords: Key words: Mast cells — Fc receptors — TNF-α— Gene regulation — RBL
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Objective: In the present study, we investigated signal transduction pathways involved in TNF-α gene expression and TNF-α secretion by mast cells stimulated through the high affinity IgE receptor (FcɛRI).¶Materials and Methods: TNF-α mRNA steady state levels and TNF-α secretion in the presence of specific pharmacological agents were monitored using rat basophilic leukemia cells (RBL-2H3) stimulated through FcɛRI. Relative amounts of TNF-α mRNA versus β-actin levels were quantified by RNase protection and RT-PCR assays. TNF-α secretion was measured by a current ELISA test.¶Results: We show that EGTA (5 mM) prevented TNF-α mRNA expression and TNF-α secretion in antigen-stimulated cells. The protein kinase C (PKC) inhibitor bisindolylmaleimide I substantially blocked TNF-α secretion at 2 μM but had only a marginal effect on TNF-α mRNA expression. The results were similar when PKC isoforms were depleted by long-term exposure to 100 nM phorbol ester (PMA). The PI 3-kinase inhibitor wortmannin blocked TNF-α secretion at low doses (EC50 = 13 nM), but only partially affected mRNA expression.¶Conclusions: Our results show that in FcɛRI-stimulated RBL-2H3 cells calcium mobilization, activation of PKC and PI 3-kinase are necessary for TNF-α secretion while for the increased TNF-α mRNA expression PKC activity is dispensable and PI 3-kinase activity only partially required.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  Although allergen-specific IgE content in serum can be determined immunochemically, little is known about the relationship between this parameter and the strength of the degranulation response upon allergen triggering.Objectives:  Analyse the degranulation capacity of immunochemically defined purified and serum IgE after challenge with anti-IgE or allergen using a rat mast cell line (RBL) transfected with the α-chain of the human high-affinity IgE receptor (FcɛRI).Methods:  Purified IgE specific for 4-hydroxy-3nitrophenylacetyl, purified IgE of unknown specificity, and sera from allergic patients sensitive to Dermatophagoides pteronyssinus and Dactylis glomerata were assessed. Degranulation was measured by a β-hexosaminidase release assay after anti-IgE or allergen-specific challenge.Results:  For purified monoclonal IgE a significant correlation (r = 0.97) was found between the proportion of bound allergen-specific IgE and the strength of the degranulation response. In contrast, no correlation (r = 0.27) was detected after sensitization with serum IgE.Conclusion:  Our studies demonstrate that mast cell activation mediated through IgE from allergic patients is a result of complex relationships that are not only dependent on allergen-specific IgE content but also relate to the capacity to efficiently sensitize and trigger the signalling responses that lead to degranulation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 337 (1989), S. 187-189 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Complementary DNAs for the FceRI y-subunit were isolated from a Agtll library prepared from rat basophilic leukaemia (RBL) cells2 using oligonucleotide probes. Figure 1 shows the complete nucleotide sequence of the y cDNA, the deduced amino-acid sequence and the position in the sequence of four ...
    Type of Medium: Electronic Resource
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