Abundance of intraepithelial γδ T cells in hypertrophic obstructive but not in chronically infected adenoids

Abstract

Using quantitative morphometrics analysis of immunohistochemically stained tissue sections we compared hypertrophic obstructive adenoids (HOA, n = 10) from children without middle ear disease with chronically infected adenoids (CIA, n = 10) from children with middle ear disease. γδ T cell receptor (TCR)+ cells constituted the dominating T cell population in the surface epithelium of HOA, while αβ TCR+ cells were the dominating intraepithelial T cell population in CIA. Intraepithelially CD8+ cells dominated over CD4+ cells in both diseases. Intraepithelially B cells were not detected. The cellular composition of follicles, with B cells dominating followed by activated CD4+ αβ TCR+ cells, was the same in both groups. However, the number of follicles in CIA was twice as many as in HOA. In the deeper interfollicular areas granulocytes were more abundant in CIA than in HOA. The latter two findings suggest a more pronounced inflammatory response in the adenoids of patients with middle ear disease. There was no significant difference with regard to pathogenic bacterial strains colonizing the adenoid surface when comparing the two patient groups. These results suggest that in patients with HOA γδ TCR+ T cells help to maintain the integrity of the surface epithelium, thereby preserving its protective function. On the basis of our results we speculate that CIA have a malfunctioning defence, thereby facilitating longstanding infections deep in the adenoid. This may be the main reason for development of middle ear disease and an indication for adenoidectomy in patients with CIA.