Application of the biotin-avidin system for ultrastructural identification of suppressor/cytotoxic lymphocytes in oral lichen planus

Immunohistochemical staining of infiltrates in oral lichen planus

Immunohistochemical examination of lymphocyte and accessory cell infiltrates was performed in 24 cases of oral lichen planus using a double staining technique. The major population of the superficial stromal lymphocytes was T cells which were mostly composed of dominant CD 4+Leu8- (helper T cells) and lesser numbers of CD 8+11b- cells (cytotoxic T cells). Contrarily, many more CD 8+11b- cells than CD 4+Leu8- cells had infiltrated the epithelium. Some infiltrated T cells expressed interleukin-2 receptor and about half of cytotoxic T cells expressed class II antigen. HLA-DR-positive monocytes were also observed in both the superficial stroma and the epithelium. A number of HLA-DR-bearing CD 1+ cells (Langerhans/dendritic cells) and CD 11c+ cells (macrophages) were observed in the lower layers of the epithelium which were sometimes degenerative. Having significant correlation with the infiltration intensities of subepithelial macrophages and epithelial CD 8+ cells (cytotoxic/suppressor T cells), epithelial Langerhans cells variably infiltrated. Superficial stromal CD 8+ cells correlated with epidermal CD 8+ and CD 4+ cell (helper/inducer T cells) infiltrates. These findings are consistent with the notion that Langerhans cells and macrophages play an important role in antigen presentation, and suggest that cellular immunity, mediated by cytotoxic T cells with helper T cells, may be related to the pathogenesis of oral lichen planus.

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

Monoclonal anti-CD4, anti-CD8, and anti-CD18 antibodies were applied in avidin-biotin-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.

Subsets of T lymphocytes in peripheral blood of patients with oral lichen planus

The T lymphocyte subsets in the peripheral blood were studied in 26 patients with oral lichen planus and in 11 normal controls. Lymphocyte subsets were identified with monoclonal antibodies (Ortho Diagnostic System Inc. Raritan, New Jersey, USA) by an indirect immunofluorescent antibody method. This study shows no significant difference between patients with oral lichen planus and healthy controls. The conclusion is that local immunity, due to the breakdown of skin-associated lymphoid tissue, not a generalized immunologic disorder, is considered to be involved in the pathogenesis of oral lichen planus.

Immunohistochemical staining of Langerhans cells and macrophages in oral lichen planus

Twenty patients with clinically and microscopically confirmed lichen planus were studied immunohistochemically. Monoclonal antibody to HLA-DR antigens and polyclonal antisera to S-100 protein and muramidase were applied to paraffin-embedded sections for the purpose of elaborating on the pathogenesis of this disease. Trypsin incubation of sections was also done in order to determine its effect on immunostaining. Langerhans cells were identified with anti-S-100 and anti-HLA-DR, and macrophages were identified with antimuramidase and anti-HLA-DR. Keratinocytes also expressed HLA-DR membrane activity in lichen planus tissue. Trypsinization significantly improved the expression of S-100 protein and muramidase antigens. It was concluded that Langerhans cells, macrophages, and keratinocytes play important roles in antigen processing and/or phagocytosis during the natural history of this disease.