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

Eur J Immunol. 1993 Dec;23(12):3230-5. doi: 10.1002/eji.1830231228.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Differentiation / analysis*
  • Antigens, Differentiation / genetics
  • Antigens, Differentiation / physiology
  • Binding Sites
  • Cytotoxicity, Immunologic*
  • Eosinophils / chemistry*
  • Eosinophils / immunology
  • Flow Cytometry
  • Galectin 3
  • Humans
  • Immunoglobulin E / physiology*
  • Lectins / analysis*
  • RNA, Messenger / analysis
  • Rats
  • Receptors, IgE / physiology


  • Antigens, Differentiation
  • Galectin 3
  • Lectins
  • RNA, Messenger
  • Receptors, IgE
  • Immunoglobulin E