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 1 700 mu mol/ 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. Copyright (c) 2007 S. Karger AG, Basel.