Immunolocalization of interleukin-4 in eosinophils in the bronchial mucosa of atopic asthmatics

Am J Respir Cell Mol Biol. 1996 May;14(5):439-43. doi: 10.1165/ajrcmb.14.5.8624248.


Several studies have shown that human eosinophils can synthesize and release a number of cytokines. The aim of this study was to investigate whether eosinophils contain interleukin (IL)-4 protein. We examined the ultrastructural localization of IL-4 in eosinophils in bronchial mucosal biopsies of 29 nonsmoking atopic asthmatics and 7 controls. No eosinophils were detected in the bronchial mucosa of controls. In the eosinophils (n = 42) of the asthmatics, IL-4 was localized to the electron-dense crystalloid core compartment of 85% of the secondary or specific eosinophil granules (n = 468). Other structures in the eosinophils were unlabeled. Control sections, incubated with an irrelevant primary antibody, were negative. This study demonstrates that pre-formed IL-4 is stored in the secondary eosinophil granules. These results were extended by light microscopic immunodouble-staining for IL-4 protein and eosinophil cationic protein, which showed that a subpopulation of activated eosinophils express IL-4 immunoreactivity in bronchial mucosal biopsies of asthmatics as well as controls. These data indicate that eosinophils may be an important source of IL-4 in allergic inflammation.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allergens
  • Asthma / immunology*
  • Asthma / pathology
  • Biopsy
  • Bronchi / immunology*
  • Bronchi / pathology
  • Cytoplasmic Granules / pathology
  • Cytoplasmic Granules / ultrastructure
  • Eosinophils / immunology*
  • Eosinophils / pathology
  • Eosinophils / ultrastructure
  • Humans
  • Immunohistochemistry
  • Interleukin-4 / analysis*
  • Microscopy, Immunoelectron
  • Mucous Membrane / immunology
  • Mucous Membrane / pathology
  • Mucous Membrane / ultrastructure
  • Reference Values


  • Allergens
  • Interleukin-4