Objective:To investigate the effects of oxidized low-density lipoprotein(ox-LDL) on the expression and activity of NAD-dependent deacetylase SIRT1 and its regulatory mechanisms on human adaptive immune function. Methods:Human primary peripheral blood monocytes were induced by human macrophage colony stimulating factor GM-CSF for 7 days in vitro. Well differentiated macrophages were treated with different concentrations(0~120 μg/ml) of ox-LDL for 48 h. The protein expression of SIRT1 was detected by Western blot. Real-time PCR was performed to examine the SIRT1 and HLA-DRα mRNA. Results:The protein expression of SIRT1 was decreased by ox-LDL in a concentration-dependent manner. The mRNA of SIRT1 treated by ox-LDL was significantly lower than that of the control group(P < 0.05).Resveratrol,which is the agonist of SIRT1,rescued the decreased expression of HLA-DRα induced by ox-LDL. Conclusion:The CIITA-dependent HLA-DRα promoter activity was decreased when treated with ox-LDL,which was induced by the change of mRNA and protein expression of SIRT1 in macrophage. Therefore,deacetylase SIRT1 may provide potential target for the treatment of atherosclerosis.