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Antineutrophil cytoplasmic autoantibodies in patients with systemic lupus erythematosus recognize a novel 69 kDa target antigen of neutrophil granules
Author(s) -
CHEN MIN,
ZHAO MINGHUI,
ZHANG YOUKANG,
WANG HAIYAN
Publication year - 2005
Publication title -
nephrology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 61
eISSN - 1440-1797
pISSN - 1320-5358
DOI - 10.1111/j.1440-1797.2005.00441.x
Subject(s) - autoantibody , medicine , antigen , immunology , proteinase 3 , western blot , cathepsin g , lactoferrin , antibody , lupus erythematosus , anti neutrophil cytoplasmic antibody , cathepsin , enzyme , pathology , biology , vasculitis , proteases , disease , biochemistry , genetics , gene
SUMMARY: Objective: Antineutrophil cytoplasmic autoantibodies (ANCA) were found in patients with systemic lupus erythematosus (SLE). Cathepsin G and lactoferrin were the major target antigens. However, some ANCA‐positive sera did not recognize either of them. The present study was to investigate the unknown target antigens of ANCA in patients with SLE and their clinical significance. Methods: Sera were collected from 72 patients with SLE. ANCA were detected in both indirect immunofluorescence and antigen‐specific enzyme‐linked immunosorbent assay (ELISA). Mixed neutrophil granules were separated from normal human peripheral neutrophils; soluble acid extracts in non‐reducing conditions were used as antigens in western blot analysis to detect ANCA. Results: SLE sera could blot a few bands. Interestingly, 14/72 (19.4%) sera recognized a novel 69 kDa protein band and 10/72 (13.9%) sera recognized the 55 kDa protein band, which might be bactericidal/permeability‐increasing protein (BPI). The 69 kDa target antigen was different from the known target ANCA antigens such as cathepsin G and lactoferrin. Further study revealed that the percentages of patients with photosensitivity and oral ulcer in the anti‐69 kDa autoantibodies‐positive group were significantly higher than those in the anti‐69 kDa autoantibodies‐negative group (57.1% vs 10.3%, P < 0.005 and 50.0% vs 12.1%, P < 0.05, respectively). Conclusions: A 69 kDa protein in human neutrophil granules was identified as a novel target antigen of ANCA in patients with SLE. The anti‐69 kDa autoantibodies might be associated with photosensitivity and oral ulcer in patients with SLE.