The relation of allergy to otitis media with effusion : Clinical and histochemical studies

Sammanfattning: Otitis media with effusion (OME) is the major form of chronic relapsing inflammatory disease of the middle ear, constitutes the most common diagnosis for chldren under 15 years old and is the major cause of auditory dysfunction in pre-school children. The aim of these studies was to determine the role of allergy in the pathogenesis of middle ear effusion that persists longer than 2 months. Allergy was diagnosed by standardized intradermal skin testing and RAST or ELISA in-vitro tests. Immunochemical techniques used to study classic allergic-rhinitis and asthma were extrapolated to the evaluation of OME. Eosinophil cationic protein (ECP), and tryptase were found in middle ear fluid in patients with OME. Initially, ECP was measured in 57 patients; 32 with persistent effusion but no recent acute infection, 14 with purulent effusion and 11 healthy subjects. Effusion ECP moved to be independent of serum ECP, was elevated only in patients proven to have allergies and was not present in allergic controls. Effusion ECP > 10μg/l correlated with allergy in a patient with OMB with a positive predictive value of 92.1% and a diagnostic sensitivity of 87.5%. ECP was established as a marker for allergy in middle ear fluid.Middle ear biopsies from 9 patients with OME were then stained histochemically for ECP. Effusion levels of ECP directly correlated with the presence of degranulating eosinophils in the mucosa (p=0.03), confirming that effusion ECP reflects an intrinsic eosinophil mediated inflammatory process.Comparison of effusion ECP in 73 individuals with OME to 16 controls found 87.7% had allergy clinically correlated to their ear disease by intradermal skin testing and history, 81.2% of whom had elevated effusion ECP.Micro-ELISA testing of paired effusion and serum samples for 12 allergens demonstrated elevated concentrations of specific IgE in the ears of 15 of 18 (83.3%) patients. There was no relationship between a patient's serum and effusion level of IgE for specific antibodies (p<0.001), suggesting the possibility that isolated local synthesis of specific IgE occurs within the middle ear.Tryptase was measured in middle ear effusions from 38 patients with OME, 94.7% of whom were atopic by ELISA testing. Tryptase was elevated only in the effusion of atopic patients as compared to 5 controls (p<0.01). Biopsies stained histochemically for tryptase showed evidence of mast cells in the mucosa and submucosa from 6 of 8 OME ears but absent in 4 normals.Conclusion: Effusion ECP, trvptase and specific IgE provide evidence that the cells andmediators essential to the production of a Th-2 immune mediated response are present in earswith chronic effusion. These studies support the hypothesis that the inflammation within themiddle ear associated with the maintenance of most cases of OME is allergic in nature.