Characteristics and outcome of Chinese patients with both antineutrophil cytoplasmic antibody and antiglomerular basement membrane antibodies.

BACKGROUND

Antineutrophil cytoplasmic antibody (ANCA)-associated systemic vasculitis (AASV) is a systemic autoimmune disease. A number of cases have been found to have antiglomerular basement membrane (GBM) antibody-positive serum. The purpose of the current article is to investigate the prevalence of anti-GBM antibodies in sera from a large cohort of Chinese patients with AASV and to characterize the clinical and pathological features of the 'double positive' patients.

METHODS

Sera from 652 patients with AASV were screened by enzyme-linked immunosorbent assay (ELISA) and confirmed by Western blot analysis using purified human alpha(IV)NC1 as antigen. Antigen specificity of anti-GBM antibodies was determined by ELISA using recombinant human alpha 3(IV)NC1 as solid phase ligand. Clinical and pathological data of patients with both ANCA and anti-GBM antibodies were analyzed retrospectively.

RESULTS

61/652 (9.36%) sera from patients with AASV were serum anti-GBM antibody positive and all recognized recombinant human alpha 3(IV)NC1. All the cases had renal involvement, 37/48 (77.1%) cases had pulmonary involvement, non-specific symptoms and other multisystem involvements were common. The renal survival was 14.6% (7/48) and patient survival was 37.5% (18/48) respectively at the end of 1 year. The following factors predicted poor prognosis: (1) serum creatinine >700 micromol/l (p = 0.034); (2) oliguria or anuria on diagnosis (p = 0.001); (3) high percentage (>85%) of glomeruli with crescents (p = 0.011); (4) high titer anti-GBM antibodies (p = 0.003), and (5) hemoptysis (p = 0.049).

CONCLUSION

Patients with double antibodies were not rare in AASV. They had multisystem involvement but poor short-term prognosis.Anti-GBM antibodies should be detected on diagnosis of AASV, especially for old ages.