Dual Role of Immunoglobulin Replacement Therapy in ANCA-Associated Vasculitis

Background: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a relapsing-remitting systemic vasculitis often requiring prolonged immunosuppression. Rituximab (RTX) is a cornerstone of induction and maintenance therapy; however, extended use can be complicated by hypogammaglobulinemia and increased infections. Immunoglobulin replacement (IgR) has been used for infection prevention in patients with secondary antibody deficiency, but its role in immunomodulation remains underexplored. Methods: We conducted a retrospective study of patients with AAV who received IgR at a single center between 2014 and 2024. Inclusion criteria included a diagnosis of AAV, treatment including RTX for induction or maintenance, documented hypogammaglobulinemia, and receipt of IgR. Clinical and treatment data were extracted from the electronic medical record. Primary outcomes were infection frequency and AAV relapses pre- and post- IgR. Secondary outcomes included changes in serum IgG and immunosuppressive therapy. Results: Sixteen patients were included, with a median age of 52 years; 75% were female, and 15 had positive ANCA. Mean serum IgG was 287 mg/dl, and 13 patients had a history of recurrent infections. Seven patients experienced disease relapse before IgR with some having recurrent flares (Table 1). After IgR, serum IgG improved in all patients, with no further infections in 14. Maintenance RTX was stopped in 10 of 14 patients; in the remaining 4, the RTX dosing interval was increased. Importantly, no disease relapses were observed after IgR. Conclusion: IgR may offer dual benefits in patients with AAV: reducing infection risk and contributing to sustained disease remission. Its role in modulating maintenance immunosuppression warrants further study.Table 1: Patient characteristics and outcomes