Abstract: Objective To investigate the clinical significance of antineutrophil cytoplasmic antibodies(ANCA) and their target antigens in systemic lupus erythematosus(SLE).Methods 84 serum samples were collected,and indirect immunofluorescence(IIF) and ELISA were used to detect the positive rates of ANCA and 6 known target antigen,the 6 specific ANCA antigens included proteinase 3 (PR3),myeloperoxidase (MPO),bactericidal/permeability increasing protein(BPI),human leukocyte elastase (HLE),cathepsin G(CG) and lactoferrin(LF) Positive sera were furthur studied by Western blot analysis.The positive rate of ANCA was also compared between patients with (n=50) and without (n=34) lupus activities to reveal whether ANCA were correlated with lupus activities Results 22.6% sera showed ANCA positive by IIF method,and all of them were peripheral nuclear ANCA However,ELISA testing showed that 44 1% and 14.3% sera recognized CG and LF,respectively The positive rates of anti CG,and anti LF antibodies in patients with active lupus were significantly higher than those in non active patients (P<0.001).Conclusion The target antigen of ANCA in SLE patients was CG,and anti CG antibodies might be correlated with lupus activities.

Key words: Lupus erythematosus,systemic, Antineutrophil cytoplasmic antibodies