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BACKGROUND: We investigated basement membrane (BM) disruption and the distribution of mast cells (MCs) and T cell subsets, in oral lichen planus (OLP) and normal buccal mucosa (NBM) using immunohistochemistry. In OLP, there were increased numbers of tryptase+ MCs in areas of BM disruption (P < 0.05). METHOD: We identified clusters of intraepithelial CD8+ T cells in OLP, specifically in regions of BM disruption. The number of intraepithelial CD8+ T cells in regions of BM disruption was significantly greater than in regions of BM continuity (P < 0.05). RESULTS: There were comparable numbers of lamina propria CD8+ T cells in regions of BM disruption and BM continuity. The number of CD4+ T cells in the epithelium and lamina propria of OLP lesions did not vary between regions of BM disruption and BM continuity. CONCLUSION: These data suggest a role for MCs in epithelial BM disruption in OLP. CD8+ T cells may migrate through BM breaks to enter the OLP epithelium.
Zhou et al. (Tue,) studied this question.