Abstract: Objective: To compare the expression of B7-H1 and PD-1 on peripheral blood T cells in oral lichen planus (OLP) patients and controls, and to explore its relationship with the disease. Methods: Twenty-two patients of OLP and twelve healthy adults were chosen. The scores of OLP disease activity were assessed according to the REU scoring system and the visual analogue scale (VAS) as described in the previous studies. Peripheral blood mononuclear cells (PBMCs) were isolated by density gradient centrifugation. The expression of B7-H1 and PD-1 on T cells in PBMCs were tested by two-color flow cytometry. After monocyte cells were removed by adhesion, the lymphocyte cells of OLP patients and controls were mixed for culture using anti-B7-H1 mAbs to block the B7-H1/PD-1 pathway, then the proliferation of lymphocyte cells were detected through XTT method after 5 days. Results: Significant differences were found among OLP patients and controls in the expression of B7-H1 and PD-1 on T cells (P﹤0.05). The expression of B7-H1 on T cells in OLP positively associated with the disease activity score (P=0.002). However, there had no relationship between the expression of PD-1 on T cells and the disease activity score in OLP (P=0.537). After blocking the B7-H1/PD-1 pathway with anti-B7-H1 mAbs, the proliferation of T cells was not significant different between the control group and the OLP group after mixed lymphocyte cell cultures (P>0.05). Conclusion: The results indicated that B7-H1 and PD-1 might play important roles in the pathogenesis of OLP. B7-H1 in T cells might relate with the progression of OLP disease.

Key words: Oral lichen planus , B7-H1/PD-1 pathway, T cells , Mixed lymphocyte culture