T cell antigen receptor expression by intra-epithelial lymphocytes in oral lichen planus

The distribution of T lymphocytes expressing the alpha beta or gamma delta heterodimer of the T cell receptor (TCR) was examined in normal oral mucosa (NOM) and reticular oral lichen planus (OLP) using a panel of antibodies specific for CD3, the alpha beta TCR and the gamma delta TCR. Intra-epithelial lymphocytes were counted and epithelial surface length was measured by image analysis. T cells in the lamina propria were not quantified. Total intra-epithelial lymphocytes were increased in OLP compared with NOM (P = 0.0004). The proportions of cells expressing the gamma delta TCR in NOM and OLP were 10% and 9.3%, respectively, suggesting there is no selective recruitment from the circulation of either alpha beta or gamma delta TCR-bearing cells into normal oral epithelium or that affected by OLP. The role, if any, of gamma delta T cells in the pathogenesis of OLP remains to be determined.