Role of local immunoglobulin E production in the pathophysiology of noninvasive fungal sinusitis

Abstract

<h4>Objectives/hypothesis</h4>Immunoglobulin (Ig)E-mediated hypersensitivity to fungi has been postulated to explain allergic fungal sinusitis (AFS). Not all patients suspected to have AFS demonstrate systemic evidence of allergy. Locally produced IgE might explain those patients with no systemic evidence of allergy but clinical features of AFS. The aim was to determine whether fungal-specific IgE could be demonstrated in sinus mucin in patients with eosinophilic mucin rhino-sinusitis.<h4>Study design</h4>A prospective study was undertaken in a tertiary rhinology practice in Adelaide, South Australia.<h4>Methods</h4>: Eighty-six consecutive patients with nasal polyposis and thick, colored macroscopically "fungal-like" sinus mucin at time of surgery for chronic sinusitis were entered in the study. The sinus mucin was liquefied and underwent testing for fungal-specific IgE (Pharmacia UniCAP) and fungal culture. Serum fungal-specific and total IgE, eosinophil count, C-reactive protein (CRP), and eosinophilic cationic protein (ECP) were measured.<h4>Results</h4>Fifty-six (65%) patients were fungal culture positive, and 37% had a detectable fungal-specific IgE in sinus mucin. Data were available to classify 81 patients: AFS = 24 (30%), AFS-like = 6 (7%), nonallergic eosinophilic fungal sinusitis = 32 (40%), nonallergic, nonfungal eosinophilic sinusitis = 19 (23%). Patients with AFS were significantly more likely to have fungal-specific IgE in sinus mucin (17/24, 71%, P =.02). In all fungal culture-positive patients, positive mucin fungal-specific IgE was significantly associated with systemic fungal allergy (P =.005), but a raised total serum IgE was not. Six (19%) of the 32 patients with positive fungal cultures but negative serum fungal-specific IgE had a positive mucin fungal-specific IgE, suggesting that they may be reclassified as AFS. The mean ECP and total IgE were raised most significantly in the AFS subgroup.<h4>Conclusions</h4>This is the first study to show that fungal-specific IgE may be demonstrated in sinus mucin. It was significantly associated with systemic fungal allergy and may play a role in a minority of fungal sinusitis patients in the absence of systemic fungal allergy.