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

Marie José Truong, Valérie Gruart, Fu-Tong Liu, Lionel Prin, André Capron, Monique Capron

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84 Scopus citations

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 (εBP). In the present study, we show by different experimental approaches that human eosinophils can express Mac-2/εBP. 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 εBP 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.

Original languageEnglish (US)
Pages (from-to)3230-3235
Number of pages6
JournalEuropean Journal of Immunology
Volume23
Issue number12
StatePublished - Dec 1993

Keywords

  • Cytotoxicity
  • Eosinophils
  • IgE-binding molecules
  • Lectins

ASJC Scopus subject areas

  • Immunology

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    Truong, M. J., Gruart, V., Liu, F-T., Prin, L., Capron, A., & Capron, M. (1993). IgE-binding molecules (Mac-2/εBP) expressed by human eosinophils. Implication in IgE-dependent eosinophil cytotoxicity. European Journal of Immunology, 23(12), 3230-3235.