Background: Cell-mediated immune responses in oral lichen planus (OLP) may be regulated by cytokines and their receptors.
Methods: In situ cytokine expression and in vitro cytokine secretion in OLP were determined by immunohistochemistry and ELISA.
Results: The majority of subepithelial and intraepithelial mononuclear cells in OLP were CD8+. In some cases, intraepithelial CD8+ cells were adjacent to degenerating keratinocytes. CD4+ cells were observed mainly in the deep lamina propria with occasional CD4+ cells close to basal keratinocytes. Mononuclear cells expressed IFN-gamma in the superficial lamina propria and TNF-alpha adjacent to basal keratinocytes. Basal keratinocytes expressed TNF-alpha as a continuous band. TNF R1 was expressed by mononuclear cells and basal and suprabasal keratinocytes. There was variable expression of TGF-beta1 in the subepithelial infiltrate while all intraepithelial mononuclear cells were TGF-beta1-. Keratinocytes in OLP stained weakly for TGF-beta1. Unstimulated OLP lesional T cells secreted IFN-gamma in vitro. TNF-alpha stimulation down-regulated IFN-gamma secretion and up-regulated TNF-alpha secretion. IL-4, IL-10 and TGF-beta1 secretion were not detected.
Conclusions: These data suggest the development of a T helper 1 immune response that may promote CD8+ cytotoxic T-cell activity in OLP.