Antigen challenge induces a supraglottic but not a subglottic edema in the rat larynx

Abstract

Problem: To examine the reaction of mast cells in the larynx of sensitized rats after allergen challenge and determine whether a type I hypersensitivity reaction can elicit a subglottic edema. Methods: Sprague-Dawley rats were sensitized with Ovalbumin (OA) and challenged 3 weeks later by intravenous injection of either OA or NaCl. Blood was withdrawn for IgE analysis and the animals perfused with glutaraldehyde under anesthesia. The larynges were removed and processed for light- and electron microscopy. Sections cut from the epiglottis and subglottic region were examined morphologically and the mast cells were quantified. Results: The IgE was significantly higher in sensitized rats compared with controls. In OA-challenged animals the mucosal mast cells (MMC) in the epiglottis epithelium and the connective tissue mast cells (CTMC) in the submucosa were significantly reduced compared with controls and the connective tissue had a marked oedematous appearance. In the subglottic region the number of both MMC and CTMC was reduced (but not significantly so) and there was no indication of morphological edema in the lamina propria. Conclusion: In sensitized rats an allergen challenge induces a marked edema in the epiglottis but not in the subglottic area. The results indicate that in the larynx, the supraglottic and subglottic regions react differently to allergen challenge. Significance: The results add interesting information to the etiology of laryngeal edema. Support: The study was supported by grants from the Faculty of Medicine, University of Umea.