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IgE-binding molecules (Mac-2/εBP) expressed by human eosinophils. Implication in IgE-dependent eosinophil cytotoxicity

Abstract : Macrophage cell-surface protein 2 (Mac-2), a galactose specific S-type lectin identified in inflammatory macrophages, presents a high degree of homology with the rat IgE-binding protein (epsilon BP). In the present study, we show by different experimental approaches that human eosinophils can express Mac-2/epsilon BP. Flow cytometry analysis revealed that a large proportion of eosinophilic patients expressing binding sites for IgE on their eosinophil membrane, were able to bind anti-Mac-2 monoclonal antibody (mAb). Northern blot performed with eosinophil RNA hybridized with the human Mac-2 or epsilon BP cDNA probes revealed that eosinophils presented a unique transcript at 1.2 kb. Immunoprecipitation of eosinophil extracts with anti-Mac-2 mAb revealed the presence of a molecule of 29 kDa corresponding to Mac-2 protein, as well as one additional molecule of 15 kDa, absent from control alveolar macrophages. The function of these molecules was investigated in a radiolabeled IgE binding assay. Anti-Mac-2 mAb as well as galactose and lactose saccharides significantly inhibited the binding of radiolabeled human myeloma IgE protein to eosinophils. Moreover, the dose-dependent inhibition by anti-Mac-2 mAb of IgE-dependent eosinophil-mediated cytotoxicity towards parasite targets indicated the role of these IgE-binding molecules in the function of human eosinophils. These results suggest that in addition to transmembrane receptors, lectin-type molecules can participate in the IgE-dependent effector function of eosinophils.
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Contributor : Valérie Gouilleux <>
Submitted on : Tuesday, December 10, 2019 - 2:31:58 PM
Last modification on : Friday, January 10, 2020 - 4:12:17 PM

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Marie-José Truong, Valérie Gruart, Fu-Tong Liu, Lionel Prin, André Capron, et al.. IgE-binding molecules (Mac-2/εBP) expressed by human eosinophils. Implication in IgE-dependent eosinophil cytotoxicity. European Journal of Immunology, Wiley-VCH Verlag, 1993, 23 (12), pp.3230-3235. ⟨10.1002/eji.1830231228⟩. ⟨hal-02402446⟩

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