Measuring Circulating Complement Activation Products in Myeloperoxidase– and Proteinase 3–Antineutrophil Cytoplasmic Antibody–Associated Vasculitis

Objective There is accumulating evidence that complement activation is important in antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV) pathogenesis. This study was undertaken to investigate complement activation in AAV with myeloperoxidase (MPO) positivity and AAV with proteinase 3 (PR3) positivity after determining optimal methods for measuring activated complement factors in circulation. Methods Participants included 98...