Distribution of mucins and antimicrobial substances lysozyme and lactoferrin in the laryngeal subglottic region.

The subglottic region of the larynx is of high clinical relevance with regard to infections and malignancies. Little is known about the distribution of mucins and antimicrobial substances in this area. In this study, we have investigated the mucin distribution in the normal subglottis of the larynx. Moreover, we analysed the expression of lysozyme and lactoferrin in this area. Therefore, the subglottic region of 34 larynges was investigated immunohistochemically with different antibodies to mucins and antimicrobial substances. The epithelium reacted positive with antibodies to mucins MUC1 (34/34), 5AC (26/34), 5B (10/34), 7 (8/34), 8 (10/34) and 16 (19/34); submucosal glands were positive to mucins MUC1 (34/34), 5B (10/34), 7 (8/34), and 16 (19/34); high columnar epithelial cells and serous parts of subepithelial seromucous glands were also positive for lysozyme (34/34) and lactoferrin (34/34). The results show that human subglottic epithelium and subepithelial submucosal glands produce a broad spectrum of mucins that is almost comparable with that in other areas of the respiratory tract. We hypothesize that the mucin diversity of the subglottis has an impact on positive functional consequences during vocal production and antimicrobial defence. This antimicrobial defence is supported by synthesis and secretion of antimicrobial substances such as lysozyme and lactoferrin. Moreover, knowledge of the observed distribution pattern of mucins in the subglottis can be a useful tool for a classification of subglottic laryngeal carcinomas.