Oral lichen planus: an immunoperoxidase study using monoclonal antibodies to lymphocyte subsets.

Sixteen biopsies from patients with oral lichen planus (10), simple keratosis (3) and lichenoid reactions (3) were studied using monoclonal antibodies directed against lymphocyte markers. T lymphocytes predominated in the cellular infiltrates of the epithelium and lamina propria of all biopsies, and cells positive with Leu 3a and Leu 2a antibodies were also present at both sites in all specimens. However, many of the Leu 3a positive intraepithelial cells had a dendritic appearance and distribution consistent with their being Langerhans cells. Limited results from cell counts on three lichen planus specimens suggested that the majority of intraepithelial T cells were of the cytotoxic/suppressor phenotype (OKT3 and Leu 2a positive).