Background: This study was designed to measure the involvement of eosinophils, neutrophils, and mast cells in the middle ear of patients with OME and to see whether that inflammatory response differed depending on whether or not the patient was atopic.
Methods: Levels of ECP, MPO, and tryptase were measured in effusion from 97 patients whose atopic status was determined by in vitro testing with 12 inhalants and five foods.
Results: Seventy-nine of 97 OME patients (81%) were atopic, among whom 86% (68/79) had elevated levels of effusion ECP, and 64% (23/36) had elevated tryptase. Mean ECP was 166 μg/l vs 3.38 μg/l, mean MPO was 6231 μg/l vs 116 μg/l, and mean tryptase was 4.8 μg/l vs 1.34 μg/l in atopic vs nonatopic ears. Total serum IgE did not differ between atopics and nonatopics (P=0.28).
Conclusions: The inflammatory response by eosinophils, neutrophils, and mast cells in the middle ear was distinctly different between atopic and nonatopic patients (P<0.001). This study provides evidence that eosinophils and mast cells, both essential to a Th-2 driven immune response, are present in the majority of ears with chronic OME, and supports the hypothesis that middle-ear mucosa, like that of the rest of the upper respiratory tract, is capable of an allergic response.