Objective To investigate the expression of the peripheral blood retinoid-related orphan receptor γt（RORγt） and 4-1BB/4-1BBL mRNA in oral lichen planus（OLP） patients.Methods The expression levels of peripheral blood’RORγt mRNA and 4-1BB/4-1BBL mRNA of 30 samples of OLP patients and 30 cases of healthy human were detected using real-time fluorescent quantitative-polymerase chain reaction（FQ-PCR） technology. Results In the OLP group, the expression level of RORγt, 4-1BB, 4-1BBL mRNA were higher than those in the control group
（P0.05）, the expression levels of 4-1BB and 4-1BBL mRNA had a positive correlation（r=0.455 0, PConclusion The abnormal expression of RORγt, 4-1BB and 4-1BBL mRNA may play certain roles in the pathogenesis of OLP.
