ALTERATION OF CYTOKERATIN EXPRESSION IN ORAL LICHEN-PLANUS

The purpose of this investigation is to examine the possible biochemic al and topographic cytokeratin alterations in lichen planus of oral mu cosa. Biopsy samples of clinically normal buccal mucosa (n = 5), norma l gingiva (n = 5), lichen planus from buccal mucosa (n = 5), and liche n planus from gingiva (n = 5) were obtained from patients of both sexe s. Cytokeratin expression was determined by means of immunohistochemic al labeling with use of a battery of monoclonal antibodies against cyt okeratins and filaggrin and two-dimensional gel electrophoresis. In bu ccal mucosa, which is not keratinized, cytokeratins 4 and 13 are expre ssed in the majority. In buccal mucosa lichen planus, the appearance o f cytokeratins 1, 2, 10, and 11 coincides with a decrease in cytokerat ins 4 and 13 and a moderate increase in cytokeratins 6, 16, 17, and 19 . In normal gingiva, which is normally keratinized, the main cytokerat ins are 1, 2, 10, and 11. In gingival lichen planus, a slight decrease in these cytokeratins and in cytokeratin 13 expression was noted. Fin ally, alterations in cytokeratins 5 and 14, explained by marked altera tions of basal cells, were observed. The battery of antibodies used in this study, in correlation with two-dimensional gel electrophoresis, could represent useful diagnostic tools that enable the distinction be tween inflammatory keratosis and so-called quiescent lichen planus. Mo reover, this work showed that cytokeratins 1, 2, 10, and 11 and filagg rin are sensitive tools that may help detect early relapse before clin ical exacerbation. Finally, these biochemical techniques may be useful to follow the evolution of lichen planus under treatment.