Background: Allergic sensitization of the airways occurs in the mucosa of the shock organ, or in the lymphatic stations draining these structures. The lymphatic structure closest to the nasal mucosa is the adenoid.
Objectives: The objective of this study was to find evidence for our hypothesis that allergic sensitization can occur in the adenoid. Of special interest, in this context are cell types involved in antigen-allergen presentation (e.g. Langerhans cells) and effector cells of allergic disease.
Methods: In this study cellular infiltrates in adenoids of 16 allergic patients and 16 age- and gender-matched controls were evaluated. The number of cells positive for CD1a, CD4, CD8, CD-68, chymase, tryptase, IgE, MBP and cells positive for interleukin (IL)-4 were determined using immunohistochemical staining techniques. The epithelium, follicles and the interfollicular spaces were evaluated separately.
Results: When comparing the two groups a significant increase in cells positive for CD1a was found in interfollicular spaces of the allergic group (P = 0.008). CD1a+ cells in the follicular space and eosinophils in the interfollicular space showed a trend to be more numerous in the allergic group (P = 0.02 and P = 0.05, respectively). The other cell types investigated did not show significant differences between the groups.
Conclusions: The results of this study show for the first time that cells involved in allergic sensitization and allergic disease differ in the adenoid of allergic children compared with controls. These findings support our hypothesis that allergic sensitization takes place in the adenoid. Furthermore, this study confirms that CD1a+ (Langerhans) cells are involved in allergic disease.