Immunoelectron microscopic study of distribution of T cell subsets in oral lichen planus

Abstract – Monoclonal anti-CD4, anti-CD8, and anti-GD18 antibodies were applied in avidinbiotin-peroxidase complex staining using a pre-embedding immunoelectron microscopy technique. Although most of the local T cells in situ were of CD4⁺ subtype, local CD8⁺ cells generally had a lower nucleus/cytoplasm ratio and contained more cell organelles than CD4⁺ cells. This suggests a local activation of CD8⁺ subpopulation, rather than activation of the numerically predominant CD4⁺ cells. Topographical analysis disclosed that all lymphocytes, regardless of location, were CD18⁺ and that most of the CD8 ⁺ cells were located subbasally and intraepithelially, whereas CD4⁺ cells often occurred in small clusters deeper down in the subepithelial lymphocyte-rich band. Furthermore, CD8⁺ cells were often in close contact with macrophages, whereas CD4⁺ cells were in some instances in direct contact with plasma cells. This indicates that CD4⁺ cells may be involved in T cell-dependent B cell-mediated immunoglobulin synthesis, whereas CD8⁺ cytotoxic lymphocytes and tissue macrophages may be involved in the local pathogenetic process leading to basement membrane alterations.