Distribution of dendritic cells and macrophages in the nose with special reference to site-dependent differences: A cadaveric study.

BACKGROUND

Macrophages and interdigitating dendritic cells (DCs) are key professional antigen-presenting cells. However, DCs appear to be absent in healthy nasal mucosa, despite the extensive ciliated respiratory epithelium being highly exposed to various antigens.

METHODS

Using histological specimens from 20 elderly cadavers, we examined the distribution of immunoreactive cells in the nasal vestibular skin, mucocutaneous junction, and ciliated mucosa. CD1a, CD83 and DC-SIGN were used as DC markers, with the latter two being typically employed in lymphatic tissue studies.

RESULTS

Macrophages and CD8-positive lymphocytes were widely distributed throughout the subcutaneous and submucosal tissues at all epithelial depths. These cells were occasionally found embedded within both the mucocutaneous junction epithelium and basal layer of the mucosal epithelium. In contrast, CD4-positive lymphocytes were scarce across all examined sites. CD169-positive macrophages, considered the first-line gatekeepers in lymphatic tissues, were localized along deep vessels and glands. CD1a-positive DCs (Langerhans cells) were absent from both the cytokeratin 14-negative squamous epithelium and ciliary epithelium but were abundant in the basal layer of the cytokeratin 14-positive stratified squamous epithelium. CD1a-positive cells, which exhibit either a dendritic or round morphology, were occasionally scattered through the elastic fiber-rich subcutaneous tissue. A few DC-SIGN- or CD83-positive DCs were seen in glands and along deep vessels in subcutaneous and submucosal tissues

CONCLUSION

Hair follicles at the nasal vestibule were likely accompanied by a cluster of CD1a-positive cells and CD8-positive lymphocytes. Macrophages, rather than DCs, were likely the primary antigen-presenting cells for CD8-positive lymphocytes in aged nasal respiratory mucosa.