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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: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Blocking antibodies are defined as antibodies that compete with IgE for binding to allergens due to their specificity for those allergens. Thus, they may inhibit allergen-induced basophil and mast cell IgE-dependent mediator release both in vivo and in vitro.Objective The present study was designed to evaluate the ability of antibodies isolated from human plasma samples on a Dactylis glomerata (Cocksfoot) pollen affinity-column to inhibit the Dactylis pollen-induced histamine release from human basophils (BHR) in vitro.Methods Antibodies from Ig pools containing either high or low IgG4 anti-Dactylis pollen were purified on a Dactylis pollen affinity-column and then separated on an anti-human Igl column. Obtained Ig fractions were incubated for 30 min with Dactylis pollen allergens prior to incubation with basophils from Dactylis pollen-allergic donors. Cell supernatants were assessed for histamine content and the inhibition of BHR was calculated.Results Unlike control non-isolated Igs, the antibodies isolated on the Dactylis pollen column were able to inhibit efficiently and in a dose-dependent manner Dactylis pollen-induced BHR. The inhibitory activity was increased in isolated antibody samples that had high Ig(i4 levels. Antibodies isolated on the Dactylis pollen column, however, consisted not only of true allergen-specific (potentially blocking) antibodies but also of autoanti-Igl- binding to allergen-specific IgE and mistaken for allergen-specific antibodies, thus opening to question the involvement of the true allergen-specific antibodies in the BHR-inhibitory activity. Unlike the true allergen-specific antibodies, the autoanti-Igl were retained on and eluted from the anti-lgF column. Results showed that both the autoanti-IgE-depleted and the autoanti-IgF-containing fractions accounted for the inhibition observed with the related non-depleted sample that had been isolated on the Dactylis pollen column.Conclusion For the first time, the true blocking activity of allergen-specific antibodies is demonstrated, that is. in the absence of the autoanti-Igl which can also inhibit BHR.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 25 (1995), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Anti-idiotypic antibodies (anti-Ids) to specific IgE antibodies are formed spontaneously during an anti-allergen immune response and can be induced by immunotherapy. Although anti-Ids can down-regulate the production of IgF. antibodies, at least in experimental models, their possible role in the modulation of target cell reactivity remains ill-defined.Objective The capacity of human anti-Ids to modulate the release of histamine was examined in an in vitro system of human basophil degranillation. Anti-Ids were prepared from the serum of six Dermatophagoides pteranyssinus (DP)-hypersensitive patients suffering from atopic dermatitis and who had never been desensitized. Basophils were obtained from the blood of atopic donors. The extent of histaminc release was determined using a fluorometric assay.Results We show that: anti-Ids trigger the release of histamine in an allergen-specific, dose- and IgE-dependent manner; the release is not due to the presence of allergen and/ or anti-IgE antibodies: and that the degranulating activity can be removed by absorption with affinity-purified anti-Dp antibodies of the corresponding patient.Conclusion These results indicate that spontaneously produced human anti-Ids can modulate the reactivity of human basophils.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 8 (1978), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The amount of histamine released from blood leucocytes by allergen, the amount of allergen required to release 50% histamine and the total IgE and IgE specific for Dactyits glomerata are compared in nine hay fever patients and five control individuals. The variation with time of total IgE. of specific IgE and of the percentage of histamine released at a fixed allergen concentration, corresponding to the cellular sensitivity, is shown for one control individual with positive in vitro and skin tests, but without clinical symptoms. For four patients with a low total IgE level the evolution of these parameters during a 1 year treatment period is presented.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Experimental Cell Research 74 (1972), S. 147-155 
    ISSN: 0014-4827
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    FEBS Letters 21 (1972), S. 83-87 
    ISSN: 0014-5793
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 36 (1981), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The present work reports the results of a double-blind clinical trial, comparing the effects of hyposensitization treatment versus placebo in 33 patients with allergic rhinitis, sensitive to a crude extract of the pollen of four different grasses (Dactylis glamerata, Lolium perenne, Secale cereale, and Phlewn pratense). The distribution of these patients in the two groups was done randomly and gave two comparable groups, as far as clinical and biological features are concerned. The treatment course included five low doses of the aqueous extract followed by 12 injections of Al(OH)3-adsorbed aliquots of the same extract. Evaluation of the clinical scores was based on diary cards on which symptoms and medications were recorded. A reevaluation of the significance of the symptom and medication scores is presented and the link between both scores is studied. Particular attention is given to the methodological and statistical problems raised during this study. The non-parametric tests reveal a significant difference (P 〈 0.03) in the total clinical score between the treated and the placebo groups for the second half of the observation period, when the pathology was most intense.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 36 (1981), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study presents the pre- and post-treatment levels of specific IgE and IgG and of total IgE in the sera of two groups of grass pollen-sensitive patients, one receiving placebo injection (16 patients), the other being treated by repeated doses of a four-grass pollen extract (17 patients).Total and specific IgE were evaluated by the radioimmunological methods based on the IgE-anti-IgE interaction. IgG specific to the pollen extract was determined by a radioimmunoassay measuring protein-A bound pollen-specific antibodies (IgG). The whole immunoglobulin content specific to the allergen was quantified by a haemagglutination technique.During the treatment period, the relative variations of total IgE, and specific IgE and IgG levels are significantly different in placebo- and pollen-treated groups: 1) for total and specific IgE, were observed a relative decrease in the placebo group, and stable levels in the treated group; 2) for IgG, the level was stable in the placebo group and a relative increase was seen in the treated group.For most of the patients the specific serum IgE and IgG levels were determined also after the pollen season consecutive to the treatment. During the pollen season, the placebo group is characterized by an increase in specific IgE concentrations and stable IgG levels. The hyposensitized patients showed stable levels of specific IgE and a decrease in specific IgG during the same period.There is a significant correlation between the levels of specific haemagglutination litres and the IgG levels. After the treatment period the haemagglutination litre is significantly lower in the placebo-treated patients than in the pollen-treated ones.A significant positive correlation exists between the levels of specific IgE and IgG before and after treaiment, for the 33 patients. Moreover, during hyposensitization, the relative variations of specific IgE and IgG are highly correlated in the treated group only.No significant correlation at the P 〈 0.05 level is observed between the clinical scores and the levels of the different biological parameters.
    Type of Medium: Electronic Resource
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  • 10
    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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