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  • 1
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Results from several studies indicate that the magnitude of immediate symptoms of type I allergy caused by allergen-induced cross-linking of high-affinity Fcɛ receptors on effector cells (mast cells and basophils) is not always associated with allergen-specific IgE levels.Objective To investigate the association of results from intradermal skin testing, basophil histamine release and allergen-specific IgE, IgG1–4, IgA and IgM antibody levels in a clinical study performed in birch pollen-allergic patients (n=18).Methods rBet v 1-specific IgEs were measured by quantitative CAP measurements and by using purified FcɛRI-derived α-chain to quantify IgE capable of binding to effector cells. Bet v 1-specific IgG subclasses, IgA and IgM levels were measured by ELISA, and basophil histamine release was determined in whole blood samples. Intradermal skin testing was performed with the end-point titration method.Results Our study demonstrates on the molecular level that the concentrations of allergen-specific IgE antibodies capable of binding to FcɛRI and biological sensitivities are not necessarily associated. A moderate association was found between cutaneous and basophil sensitivity.Conclusion Our results highlight the quantitative discrepancies and limitations of the present diagnostic tools in allergy, even when using a single allergenic molecule. The quantity of allergen-specific serum IgE is only one component of far more complex cellular systems (i.e. basophil-based tests, skin tests) used as indirect diagnostic tests for IgE-mediated allergic sensitivity.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 33 (2003), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We suggest that the coapplication of recombinant allergens and microarray technology can lead to the development of new forms of multi-allergen tests which allow the determining and monitoring of complex sensitization profiles of allergic patients in single assays. The allergen extracts which have so far been used for diagnosis only allowed the determining of whether an allergic patient is sensitized against a particular allergen source, but the disease-eliciting allergens could not be identified. Through the application of recombinant DNA technology a rapidly growing panel of recombinant allergen molecules has become available which meanwhile comprises the epitope spectrum of most of the important allergen sources. We demonstrate that microarray technology can be used to establish multi-allergen tests consisting of microarrayed recombinant allergen molecules. Microarrayed recombinant allergens can be used to determine and monitor the profile of disease-eliciting allergens using single tests that require minute amounts of serum from allergic patients. The wealth of diagnostic information gained through microarray-based allergy testing will likely improve diagnosis, prevention and treatment of allergy.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background IgE-dependent activation of mast cells (MCs) is a key pathomechanism of type I allergies. In contrast, allergen-specific IgG Abs are thought to attenuate immediate allergic reactions by blocking IgE binding and by cross-linking the inhibitory Fcγ receptor IIB on MCs.Objectives To establish a defined in vitro system using human MCs to study the biological activity of allergens and to investigate the role of allergen-specific IgE and IgG.Methods Purified human intestinal MCs sensitized with different forms of specific IgE Abs were triggered by monomeric and oligomeric forms of recombinant Bet v 1, the major birch pollen allergen, in the presence or absence of allergen-specific IgG Abs.Results MCs sensitized with an anti-Bet v 1 IgE mAb or sera obtained from birch pollen allergic patients released histamine and sulphidoleukotrienes after exposure to oligomeric Bet v 1. Monomeric Bet v 1 provoked mediator release only in MCs sensitized with patients sera but not in MCs sensitized with anti-Bet v 1 IgE mAb. Interestingly, MC activation could be induced by supercross-linking of monomeric Bet v 1 bound to monovalent IgE on MCs with a secondary allergen-specific IgG pAb. By using IgG F(ab′)2 fragments we provide evidence that this effect is not a result of IgG binding to Fcγ receptors.Conclusion This assay represents a new tool for the in vitro study of MC activation in response to natural and genetically modified allergens. Fcɛ receptor I supercross-linking by allergen-specific IgG Abs provides a possible new mechanism of IgG-dependent enhancement of type I allergic reactions.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0014-5793
    Keywords: Grass pollen allergen ; Phl p II ; Type I allergy ; cDNA cloning
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 53 (1998), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A great variety of recombinant plant, mite, mold, mammal, and insect allergens have been expressed in heterologous hosts (e.g., Escherichia coli), their cDNA being used as a template. The number of biologically active recombinant allergens available for experimental, diagnostic, and therapeutic purposes is increasing tremendously. Recombinant allergens have proven to be valuable tools to investigate T-cell and B-cell recognition of allergens as well as to study mechanisms of specific IgE regulation. The immunologic equivalence of many relevant recombinant allergens with their natural counterparts has been demonstrated, and the three-dimensional structures of several recombinant allergens have been described recently. As a result of extensive cross-reactivities among the relevant allergens, it appears that the number of epitopes needed for diagnosis and specific immunotherapy is less diverse than originally anticipated and might be soon covered by recombinant molecules. Recombinant allergens have been used for successful in vitro, as well as in vivo, allergy diagnosis, and work is in progress to produce recombinant allergen derivatives with reduced anaphylactic potential to improve current forms of immunotherapy.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1615-6102
    Keywords: Actin ; Actin-binding proteins ; Gelsolin ; Micrasterias ; Microinjection ; Profilin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Recombinant profilins from different sources (Betula verrucosa, Schizosaccharomyces pombe, Acanthamoeba castellani, or man) cause marked effects on cell growth and morphogenesis when microinjected into growing cells of the green algaMicrasterias denticulata. Whereas control injections with β-lactoglobulin only result in a slight delay of cell growth, when profilin is injected cell differentiation ceases and only resumes about 1 to 2 h after the injection, depending on the dose. The resulting cell does not show any malformations, but is reduced in size and retarded in differentiation compared to controls. As a consequence of the profilin microinjection the pattern of cytoplasmic streaming and cytoplasmic structure are also altered. Gelsolin, injected for comparison, leads to minor retardation of cell development but produces less marked effects than profilin. Microinjection of fluorescently labeled profilin shows even distribution throughout the cytoplasm and more intense fluorescence in the nucleus. Electron microscopical investigations of cells fixed immediately after profilin injection show a normal distribution of dictyosomes, ER cisternae, microtubules, and secretory vesicles compared to noninjected controls at the same developmental stage. Our results indicate that disturbance of the natural actin turnover by the injection of actin-binding proteins strongly affects development ofMicrasterias, corroborating a key role of actin in the morphogenetic process.
    Type of Medium: Electronic Resource
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