Abstract： Objective To detect the expression levels of macrophage migration inhibitory factor (MIF) in peripheral blood mononuclear cells (PBMCs),sera and skin tissue fluid from patients with vitiligo vulgaris,and to investigate their clinical significance.Methods Thirty-nine patients with vitiligo vulgaris and 31 age- and sex-matched normal human controls were recruited in this study.Real-time reverse transcription-PCR was employed to assess the expressions of MIF mRNA in PBMCs,enzyme-linked immunosorbent assay (ELISA) to detect the concentrations of MIF in sera and skin tissue fluid from these subjects.Results Patients with vitiligo vulgaris showed a significantly higher level of MIF mRNA in PBMCs (6.70 (2.64 - 8.65) vs.1.67 (1.24 - 2.45),Z=5.895,P＜ 0.05),MIF protein in sera (32.76 (10.67 - 40.98) μg/L vs.7.89 (6.13 - 9.54) μg/L,Z=5.936,P ＜ 0.05 ) and skin tissue fluid ( 167.80 ( 107.40 - 219.60) μg/L vs.42.44 (32.29 - 49.74) μg/L,Z =4.715,P ＜ 0.05) compared with the normal human controls.The expression levels of MIF mRNA in PBMCs,and MIF protein in sera and skin tissue fluid were also higher in patients with progressive vitiligo than in those with stable vitiligo (7.89 (3.89 - 9.12) vs.5.62 (2.23 - 7.29),Z=2.213,P＜ 0.05; 37.80 (29.50 - 45.70) μg/L vs.22.70 (9.36 - 37.78) μg/L,Z=2.141,P＜ 0.05; 211.50 (131.70 - 248.75) μg/L vs.144.65 (89.13 - 167.30) μg/L,Z =2.100,P ＜ 0.05).In addition,the vitiligo area severity index (VASI) score was positively correlated with the expression levels of MIF mRNA in PBMCs (r =0.486,P ＜ 0.05)and MIF protein in sera (r =0.453,P ＜ 0.05).Conclusion MIF might play a certain role in the pathogenesis of vitiligo vulgaris.