Eosinophils and neutrophils in biopsies from the middle ear of atopic children with otitis media with effusion.
OBJECTIVE
The majority of patients with otitis media with effusion (OME) and atopy have been shown to have elevated levels of eosinophil cationic protein (ECP) in their middle ear fluid. The mechanism underlying these elevated levels of ECP is not clear. The purpose of this study was to investigate the feasibility of a quantitative determination of eosinophils and neutrophils in the middle ear lining by specific immunocytochemical markers, in order to study the extent of the involvement of these cells in patients with OME.


METHODS
Bilateral middle ear biopsies from five children with persistent OME and atopy confirmed by in vitro testing were evaluated for the presence of eosinophils and neutrophils with monoclonal antibodies against specific granule proteins. Five subjects who had no signs of effusion or infection but were undergoing routine tympanoplasty for dry perforations served as controls. The biopsies were embedded in a plastic resin to improve the structural preservation of the target cells and to increase the resolution in the light microscope. Dual markers were used to determine which marker was better for eosinophils and neutrophils, respectively. The following markers were used: eosinophil cationic protein (EG2), and eosinophil peroxidase (EPO) for eosinophils and myeloperoxidase (MPO) and human neutrophil lipocalin (HNL) for neutrophils.


RESULTS
Antibodies against EPO gave a more localized and intense staining than antibodies against EG2. Antibodies against HNL appear more specific to neutrophils than antibodies against MPO that also recognize monocytes. The number of cells was determined both in the tissue and in the mucus covering the epithelium. Eosinophils and neutrophils were present in the subepithelial connective tissue and in the mucus blanket in the middle ear of patients with OME in significantly higher number than in the control group. In general, there were more inflammatory cells in the mucus than in the tissue itself, but the number of inflammatory cells in the mucus showed a significant positive correlation with the number of inflammatory cells in the tissue. There was a significant positive correlation between the number of neutrophils and the number of eosinophils in the tissue as well as in the mucus, irrespective of which marker was used.


CONCLUSIONS
The results of this study show the feasibility of using specific antibodies to identify eosinophils and neutrophils in the middle ear. The initial data suggest that atopic children with OME have higher numbers of such cells as compared to non-OME controls.
Amin
K
K
Department of Medical Cell Biology, University of Uppsala, Sweden. kawa.amin@medcellbiol.uu.se
Hurst
D S
DS
Roomans
G M
GM
Venge
P
P
Sevéus
L
L
D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal; D002452:Cell Count; D002648:Child; D002675:Child, Preschool; D004432:Ear, Middle / Q000473:pathology*; D004797:Enzyme-Linked Immunosorbent Assay; D004804:Eosinophils / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009504:Neutrophils / Q000473:pathology*; D010034:Otitis Media with Effusion / Q000473:pathology*; D009195:Peroxidase / Q000276:immunology; D016613:Plastic Embedding
D000911:Antibodies, Monoclonal; D009195:Peroxidase