Reduction of epithelial dendritic cells in keratotic lesion of oral lichenplanus

The number and distribution of epithelial dendritic cells (EDC) in oral muc osal lesions are variable depending on the degree of epithelial maturation/ differentiation and disease activity Localized absence of EDC might impair mucosal immunologic protection, allow microbial colonization and enhance ca rcinogenesis. Increased number of EDC during the early stage of oral lichen planus (OLP) suggests their increased antigen-presenting capability and im munologic activity with inflammatory reaction, but their role in the proces s of heratinization remains unclear: Therefore, the purpose of this study w as to determine the number and distribution of EDC in 33 biopsy specimens f rom lesions of OLP and from 18 control specimens of leukoplakia (LPL) at si tes undergoing increased keratinization. Cells were identified immunocytoch emically by the presence of antigen CD68 and labeled with acid phosphatase (AP) and alpha-naphthyl acetate esterase (ANAE) techniques. Numbers of EDC were expressed per mm epithelial surface length. Significantly more EDC wit h prominent histoenzymatic activity of AP and ANAE were present in OLP than in LPL. Intense enzymatic activity of ANAE was expressed in EDC of OLP wit h hyperparakeratosis. In the lesions with increased keratinization the numb er of EDC was markedly reduced in OLP while in LPL remained unchanged. Redu ced number and subbasal redistribution of EDC in OLP suggest diminution of immunologic reaction and disease activity but also increased tissue vulnera bility to various antigen challenges.