Abstract: Objective To examine the expression of TLR2 in human peripheral blood mononuclear cells(PBMCs) stimulatedby Legionella.Methods Human peripheral blood mononuclear cells(POMCs) were treated with different concentrations of Legionella(2×10⁶/ml,2×10⁷/ml),and real timel reverse transcriptase PCR(RT-PCR) was used to detect TLR2 mRNA expression.Results Factorial analyses showed that leading effect of time had statistical significance(F=26.06,P<0.05) and there was an interaction between the time and concentration(F=11.39,P<0.05).In 24 hours,the expressions of TLR2 mRNA of PBMCs stimulated with 2×10⁶/ml and 2×10⁷/ml Legionella were obviously higher than TLR2 mRNA expression in control group.In 48 hours,there was no difference between stimulated group and control group.In 72 hours,the expressions of TLR2 mRNA of PBMCs stimulated with 2×10⁶/ml and 2×10⁷/ml Legionella,were obviously lower than TLR2 mRNA expression in the control group.When the PBMCs were stimulated at the level of 2×10⁶/ml and 2×10⁷/ml Legionella,the difference in the expression of TLR2 mRNA in each period was statistically significant.Conclusion Expression of TLR2 mRNA in human peripheral blood mononuclear cells with Legionella is correlated with the time and dosage in vitro.The research provides a reference for the time and dose in the study.