期刊
CLINICAL AND EXPERIMENTAL ALLERGY
卷 35, 期 6, 页码 774-781出版社
WILEY
DOI: 10.1111/j.1365-2222.2005.02248.x
关键词
allergy; Bet v 1; birch pollen; Fc epsilon receptor I; histamine; human; IgE; IgG; mast cells; recombinant allergens
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 Fc gamma receptor IIB on MCs. 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. 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. 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 Fc gamma receptors. This assay represents a new tool for the in vitro study of MC activation in response to natural and genetically modified allergens. Fc epsilon receptor I supercross-linking by allergen-specific IgG Abs provides a possible new mechanism of IgG-dependent enhancement of type I allergic reactions.
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