Abstract
Considerable progress has been made in understanding the role of autoantibodies in systemic vasculitides (SV), and consequently testing for anti-neutrophil cytoplasmic antibodies (ANCA), anti-glomerular basement membrane antibodies (anti-GBM), and anti-C1q antibodies is helpful and necessary in the diagnosis, prognosis, and monitoring of small-vessel vasculitis. ANCA-directed proteinase 3 (PR3-) or myeloperoxidase (MPO-) are sensitive and specific serologic markers for ANCA-associated vasculitides (AAV), anti-GBM antibodies are highly specific for the patients with anti-GBM antibody disease (formerly Goodpasture’s syndrome), and autoantibodies to C1q are characteristic of hypocomlementemic urticarial vasculitis syndrome (HUVS; anti-C1q vasculitis). The results of a current EUVAS study have led to changes in the established strategy for the ANCA testing in small-vessel vasculitis. The revised 2017 international consensus recommendations for ANCA detection support the primary use PR3- and MPO-ANCA immunoassays without the categorical need for additional indirect immunofluorescence (IIF). Interestingly, the presence of PR3- and MPO-ANCA have led to the differentiation of distinct disease phenotype of AAV: PR3-ANCA-associated vasculitis (PR3-AAV), MPO-ANCA-associated vasculitis (MPO-AAV), and ANCA-negative vasculitis. Further studies on the role of these autoantibodies are required to better categorize and manage appropriately the patients with small-vessel vasculitis and to develop more targeted therapy.
Highlights
Primary systemic vasculitides (SV) are a clinical heterogeneous group of syndromes that are characterized by variable degrees of inflammation of the blood vessel wall
Few of these autoantibodies are currently being used in routine practice in the diagnosis of patients with small-vessel vasculitis, such as anti-neutrophil cytoplasmic antibodies (ANCA) in ANCA-associated small-vessel vasculitis, anti-glomerular basement membrane (GBM) antibodies in anti-GBM antibody disease, and anti-C1q antibodies in immune complex-associated small-vessel vasculitis
The results are compared with two state-of-the-art ANCA indirect immunofluorescence (IIF) analyses, one based only on ethanol-fixed neutrophils and the other based on the combination of ethanol-fixed neutrophils, formalin-fixed neutrophils and HEp2 cells [24]
Summary
Primary systemic vasculitides (SV) are a clinical heterogeneous group of syndromes that are characterized by variable degrees of inflammation of the blood vessel wall. These severe and mostly rare disorders are difficult to diagnose, and the discovery that subgroups of systemic vasculitis are associated with autoantibodies against intracellular and tissue antigens has significant and prognostic implications on the diagnosis and management of the patients. Autoantibodies detected in primary systemic vasculitis are very heterogeneous with respect to their specificity and clinical significance. The objectives of the review are to present and discuss the available new data on ANCA testing in vasculitis and to give advice on the clinical indications for ANCA diagnostics; to provide some data on the mechanisms of Antibodies 2019, 8, 31; doi:10.3390/antib8020031 www.mdpi.com/journal/antibodies
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