Proliferation and apoptosis of peripheral blood mononuclear cells in patients with oral lichen planus.

Oral lichen planus (OLP) is generally accepted to be a T cell-mediated chronic inflammatory disease with an unclear pathogenesis. There have been numerous studies on the proliferation and apoptosis of T cells in situ. In contrast, research on the proliferation and apoptosis of peripheral blood mononuclear cells (PBMCs) in patients with OLP is rare. The aim of the present study was to investigate the proliferation and apoptosis of PBMCs in patients with OLP. PBMCs were isolated from 20 patients with reticular OLP, 20 patients with atrophic-erosive OLP, and 20 healthy volunteers. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-2,5-tetrazolium bromide assays were performed to investigate the proliferation of PBMCs, and caspase-3 colorimetric assays were performed to investigate the apoptosis of PBMCs. The proliferation rate of PBMCs in atrophic-erosive OLP subjects was significantly higher than that in both healthy (P < 0.05) and reticular OLP (P < 0.05) subjects. In contrast, the proliferation rate of PBMCs in reticular OLP subjects was significantly lower than that in healthy subjects (P < 0.05). The apoptosis rates of PBMCs in OLP subjects (P < 0.05) and atrophic-erosive OLP subjects (P < 0.05) were significantly lower than the apoptosis rate in the healthy group. Our findings reinforce the view that T cell-mediated immune responses play a critical role in the pathogenesis of OLP. It can reasonably be concluded that these abnormalities are linked to the presence of inflammatory infiltrates.