LAUSR

INTRODUCTION A ntineutrophil cytoplasmic antibody (ANCA)– associated vasculitis (AAV) is a small vessel necrotizing vasculitis with a predilection for the respiratory tract and kidneys. Prompt initiation of remission induction immunosuppression is paramount to prevent irreversible organ damage. Standard initial therapy for severe AAV consists of cyclophosphamide or rituximab in combination with high-dose glucocorticoids. In cases of severe pulmonary hemorrhage or rapidly progressive glomerulonephritis, plasma exchange is often added to facilitate rapid removal of ANCA. Improved understanding of disease pathogenesis has provided the rationale for targeting the complement pathway in AAV. In particular, the anaphylatoxin complement component 5a (C5a) has been identified as a key pathogenic mediator of AAV because of its ability to prime and recruit neutrophils. Inhibitors of C5a and the C5a receptor are being evaluated in randomized trials, but are not currently available for clinical use. Here, we report the use of eculizumab, a monoclonal antibody against C5, in 2 cases of aggressive AAV with the intention of rapidly inducing remission by inhibiting C5a generation. In both patients, religious beliefs prohibiting the receipt of blood products precluded the use of plasma exchange and cyclophosphamide.