Performance of a novel chemiluminescence assay for the detection of anti-pr3, anti-MPO and anti-GBM autoantibodies

Abstract

Introduction Anti-proteinase 3 (PR3), anti-myeloperoxidase (MPO) and anti-glomerular basement membrane (GBM) auto-antibodies are hallmarks in diagnosing the ANCA-associated vasculitides, granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), as well as Goodpasture’s syndrome, respectively. The objective was to analyse three novel chemi-luminescence immunoassays (CIA) on a random access chemi-luminescent auto-analyser (BIO-FLASH) for the detection of anti-PR3-, anti-MPO- and anti-GBM autoantibodies. Methods Sera from patients with GPA ( n = 81), MPA ( n = 70) and GPS ( n = 90) and from various healthy and disease controls were tested for anti-PR3( n = 990), anti-MPO ( n = 920) and anti-GBM ( n = 797). Randomly selected samples were also tested by ELISA (INOVA Diagnostics). Results Sensitivities/specificities were: 70.4%/98.2% for PR3, 79.5%/98.7% for MPO and 95.6%/99.6% for anti-GBM antibodies. The areas under the curves were 0.868 (95% CI 0.805– 0.931) for PR3, 0.948 (0.914–0.982) for MPO and 0.980 (0.958– 1.00) for GBM. Positive and negative likelihood ratios were 38.7/ 0.30 (PR3), 60.91/0.21 (MPO) and 253.86/0.04 (GBM). Good agreements were observed between ELISA and CIA. The positive, negative and total agreements were 98.2%/96.0%/96.7% for anti-PR3( n = 181), 100.0%/87.0%/91.0% for anti-MPO ( n = 167) and 98.8%/97.1%/98.3% for anti-GBM antibodies ( n = 120). Conclusion The novel CIAs showed valuable test characteristics for the diagnosis of ANCA-associated vasculitis and Goodpas-ture’s syndrome.