Objective To investigate the expression of Fc?RⅡb on peripheral blood mononuclear cells(PBMCs)and serum anti-C1q antibodies in SLE patients and their role in SLE pathogenesis.Methods The ex-pression of Fc?RⅡb on peripheral neutrophiles,lymphocytes and monocytes was detected by flowcytometry and the level of anti-C1q antibodies was tested by ELISA in32SLE patients and22healthy individials.At the same time,the correlation between Fc?RⅡb,anti-C1q antibodies and ANA,anti-dsDNA antibodies,SLEDAI was eval-uated respectively.Results The expression of Fc?RⅡb on peripheral neutrophiles,lymphocytes and monocytes(especially on neutrophiles and monocytes)of SLE patients decreased,the level of anti-C1q antibodies was signifi-cantly increased,compared with that of the control group.Fc?RⅡb was negatively and anti-C1q antibodies were positively associated with ANA,anti-dsDNA antibodies and SLEDAI respectively.Conclusion The defective ex-pression of Fc?RⅡb on PBMCs and high level of anti-C1q antibodies do exist in SLE patients.Fc?RⅡb and anti-C1q antibodies may decrease the clearance of immune complex and play an important role in the pathogene-sis of SLE.They may also be important parameters in indicating SLE activity.