Intraepithelial lymphocyte subpopulations and dendritic accessory cells in normal and hypertrophic adenoids.

The adenoids have been studied by immunocytochemistry and electron microscopy in children with and without adenoidal enlargement. Compared with normal adenoids, the enlarged ones showed a marked increase in the number of intraepithelial gamma-delta TCR+ lymphocytes and a slight increase in the number of intraepithelial CD8+ lymphocytes. This was accompanied by large amounts of dendritic human lymphocyte antigen (D related) (HLA-DR+) S-100+ accessory cells in the lymphoid tissue underlying the epithelium. By electron microscopy, dead epithelial cells apposed to intraepithelial lymphocytes, and clefts of the epithelial lamina, could be seen frequently in the enlarged adenoids, whereas, in the normal ones, they could not. Based on these findings, the hypothesis is drawn that imbalance of the system of the intraepithelial cytotoxic lymphocytes may lead to increased killing of epithelial cells and uncontrolled penetration of exogenous agents, and hence be involved in the pathogenesis of adenoidal hypertrophy.