The role of complement in antineutrophil cytoplasmic antibody-associated vasculitisWester Trejo, Maria A.C.a; Trouw, Leendert A.b; Bajema, Ingeborg M.aCurrent Opinion in Rheumatology: January 2019 - Volume 31 - Issue 1 - p 3–8 doi: 10.1097/BOR.0000000000000557 VASCULITIS SYNDROMES: Edited by Hasan Yazici and Yusuf Yazici Abstract Author InformationAuthors Article MetricsMetrics Purpose of review To provide a comprehensive overview of the current insight into the role of complement activation in antineutrophil cytoplasmic antibody-associated vasculitis (AAV). In addition, the therapeutic options targeting the complement system in AAV are discussed. Recent findings It has become increasingly clear that complement, and more specifically signalling through the C5a receptor, contributes to the immunopathology of AAV. This has led to the design of clinical trials with a C5a receptor blocker. The first results show a reduction in tissue damage and a favourable safety profile, as other parts of the complement defence system are left intact. Summary Although AAV was initially regarded as a pauci-immune disease, it is now well established that, in addition to autoantibodies, complement plays an essential role in the disease process. Animal models delivered the first insight, but the effective therapeutic interventions using complement inhibitors provided the proof that indeed complement activation contributes to disease activity and tissue damage in human AAV. aDepartment of Pathology bDepartment of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, the Netherlands Correspondence to Maria A.C. Wester Trejo, Department of Pathology, L1-Q (P0–107), Leiden University Medical Center, PO BOX 9600, 2300 RC Leiden, the Netherlands. Tel: +31 71 5266574; e-mail: firstname.lastname@example.org Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.