Immunolocalization of interleukin-4 in eosinophils in the bronchial mucosa of atopic asthmatics.
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.
Möller
G M
GM
Department of Pulmonary Diseases, Erasmus University, Rotterdam, The Netherlands.
de Jong
T A
TA
van der Kwast
T H
TH
Overbeek
S E
SE
Wierenga-Wolf
A F
AF
Thepen
T
T
Hoogsteden
H C
HC
D000485:Allergens; D001249:Asthma / Q000276:immunology* / Q000473:pathology; D001706:Biopsy; D001980:Bronchi / Q000276:immunology* / Q000473:pathology; D003594:Cytoplasmic Granules / Q000473:pathology / Q000648:ultrastructure; D004804:Eosinophils / Q000276:immunology* / Q000473:pathology / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D015847:Interleukin-4 / Q000032:analysis*; D016253:Microscopy, Immunoelectron; D009092:Mucous Membrane / Q000276:immunology / Q000473:pathology / Q000648:ultrastructure; D012016:Reference Values
D000485:Allergens; D015847:Interleukin-4