Immunohistochemical demonstration of T cell subsets and accessory cells in oral lichen planus

Abstract

The nature and distribution of mononuclear cells in 30 non‐ulcerated lesions of oral lichen planus (OLP) was investigated, using an immunoperoxidase technique. Most of the infiltrating cells consisted of a mixture of Leu 2a+ and Leu 3a+/3b+ T cells present in the stroma. This study proved histometrically that the emigration of lymphocytes through subepithelial vessels was not selective for major subsets of T cells and subsequent migration to the epithelium was predominant in suppressor/cytotoxic T cell infiltration. HLA‐DR+/DQ+ monocyte/macrophage and Langerhans cells formed a relatively minor component of the cellular infiltrates, whereas a considerable number of T cells expressed the MHC antigens. Also, the keratinocytes of the epithelium expressed only DR antigens. These results support the concept that LP is associated with lymphokine‐generated inflammation induced by helper/inducer T cells or activated T cells which would include direct basal cell damage or local immunosuppression by suppressor/cytotoxic T cells. Furthermore, this study suggests that monocytes/macrophages and Langerhans cells played a role in antigen presentation, and also that keratinocytes may possess a similar function.