FoxP3(+) T regulatory cells in oral lichen planus and its correlation with the distinct clinical appearance of the lesions

The aim of this study was to evaluate the presence of FoxP3⁺ cells in oral lichen planus (OLP) and to correlate the findings with clinical and histopathological features of these lesions. The sample consisted of 32 cases of OLP (17 reticular and 15 erosive cases) and 10 cases of inflammatory fibrous hyperplasia (IFH). Clinical examination, histopathological and histomorphometric analysis, and immunohistochemistry (anti‐FoxP3 antibody) were performed. Cells were counted in juxtaepithelial and intraepithelial regions of the lesions, and the results are expressed as the mean and range. Most erosive lesions were keratinized and exhibited epithelial atrophy, whereas most reticular lesions were hyperkeratinized. Mean epithelial thickness and mean density of the inflammatory infiltrate were higher in reticular lesions than in erosive OLP. Juxtaepithelial FoxP3⁺ cells were slightly more frequent in erosive lesions (mean: 1.7 and range: 0–9.4) than in reticular lesions (mean: 1.5 and range: 0–8.3). There was a significant difference in the frequency of these cells between OLP (mean: 1.6 and range: 0–9.4) and IFH (mean: 0.5 and range: 0–1.4) (P < 0.05). The number of intraepithelial FoxP3⁺ cells was higher in reticular OLP and IFH when compared with erosive lesions. The larger number of juxtaepithelial FoxP3⁺ cells in OLP compared to IFH might be related to the distinct etiopathogenesis of these lesions. High disease activity or action of the oral microbiota may explain the slightly higher frequency of FoxP3⁺ cells in erosive lesions.