Identification of antileucoprotease in remodelled human adult nasal surface epithelium.

Antileucoprotease (ALP) is generally considered as a specific marker for glandular serous cells, and plays a major role in the defence of the respiratory tract against proteolytic damage. Nevertheless, several studies have identified ALP in bronchial and bronchiolar surface epithelial cells, and also an increased number of ALP-containing cells in bronchiolar tissue during the development of pulmonary diseases. In order to define more clearly whether the surface epithelium might be involved in the defence of the respiratory mucosa, we have investigated the expression of ALP by cells of the nasal surface epithelium. Indirect immunocytochemistry and in situ hybridization for ALP were performed on human nasal polyp sections. The height of the surface epithelium, its morphology, and the degree of local inflammation were assessed in parallel. Surface epithelium morphology was highly heterogeneous. ALP-containing cells were identified, but only in remodelled areas of the surface epithelium (foldings, basal cell and/or mucous cell hyperplasia), with no association to the degree of inflammation. These results demonstrate that the surface epithelial cells of the human adult nasal mucosa can express ALP in remodelled surface epithelium, and may be actively involved in the biochemical defence of the airways.