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.