Abstract: Objective To investigate the role of abnormal expression of DNA methyltransferases (DNMT1,DNMT3A,DNMT3B)and CD11a genes in the pathogenesis of systemic lupus erythematosus (SLE).Methods Semiquantitative reverse transcriptase-polymerase chain reaction was applied to detect the mRNA expression levels of DNMTs and CD11a in PBMCs of relieved(n=17),active(n=17)SLE patients and healthy controls(n=17).The correlations were further analyzed between these parameters. Results The expression of DNMT1 was significantly lower in PBMCs of both relieved and active SLE patients than that of health controls(t=5.90,P<0.0001;t=2.26,P=0.0001 respectively).No significant difference was observed in DNMT1 expression between relieved and active SLE patients(t=1.75,P=0.089),or in the expression of DNMT3A in PBMCs between relieved,active SLE patients and healthy control.The expression of DNMT3B in PBMCs was extremely low.The expression of CD11a was significantly higher in relieved SLE patients than in the healthy controls(t=5.35,P<0.0001),in active SLE patients than in relieved SLE patients(t=2.99,P=0.006)and healthy controls(t=6.57,P<0.0001). No significant correlation was observed between the decrease of DNMT1 and SLE disease activity index (SLEDAI)(r=-0.34,P>0.05),or between the expression level of DNMTI and CD11a(r=-0.18, P>0.05).The increase of CD11a positively correlated with SLEDAI(r=0.48,P<0.05).Conclusion The decreased expression of DNMT1 may play an important role in the pathogenesis of SLE,but not the only factor contributing for DNA methylation status.

Key words: Lupus erythematosus,systemic, DNA modification methylases, Antigens,CD11a