Allergenic fungi in allergic fungal sinusitis

Background: Patients with allergic fungal sinusitis demonstrate skin test reactivity to many fungal extracts. Various fungi have been isolated from the characteristic allergic mucin. Objective: This study was designed to identify allergens in allergic mucin and to compare them to those found in commercial fungal extracts. Methods: Allergic mucin was collected during functional endoscopic sinus surgery from 11 patients meeting strict diagnostic criteria for allergic fungal sinusitis and from three allergic rhinitis patients with chronic sinusitis. A portion was solubilized in saline and centrifuged. To identify allergens, proteins in allergic mucin and fungal extracts were separated by SDS-polyacrylamide gel electrophoresis, transferred to nitrocellulose and immunostained using patient sera and enzyme-labeled anti-human IgE. Results: All patient sera recognized numerous bands ranging from 18 to 90 kD. In mucin, bands were consistently found in the 35 to 50 kD range. Corresponding bands in fungal extracts were found in only 1/11 patients with allergic fungal sinusitis. Sera from 4/11 patients detected an 18-kD protein in allergic mucin, but sera from all patients with allergic fungal sinusitis recognized an 18-kD protein in commercial fungal extracts. Sera from selected patients with allergic fungal sinusitis detected human epithelial proteins in the 35 to 50 kD range. Conclusions: Fungal allergens were not detected in allergic mucin of all patients with allergic fungal sinusitis. The 18-kD allergen appears to be shared by many fungi, and may be a fungal panallergen. The source of the apparent allergens in the 3550-kD range warrants further study.