AB0038 Differential Outcome of B Cell Depletion in Patients with Anca-Associated Vasculitis (AAV) Compared to Patients with Systemic Lupus Erythematosus (SLE): Table 1.

Background B lymphocytes play a fundamental role in adaptive immune responses against pathogens. However, self-reactive memory B cells and long-lived plasma cells are a hard-to-hit target in patients with autoimmune diseases. Clinical trials with the B cell depleting CD20-antibody rituximab (RTX) revealed mixed results, with a benefit in patients with rheumatoid arthritis (RA) or AAV but less consistent results in patients with SLE. Objectives To investigate the influence of B cell depletion by RTX on circulating B cells from patients with AAV and SLE. Methods Peripheral blood samples of 12 AAV and 9 SLE patients were obtained prior and 8-12 weeks post RTX treatment and B lymphocyte subsets were analyzed by multiparameter flow cytometry. In addition, changes in immunoglobulin, free light chain (FLC), autoantibody, and BAFF serum levels were determined at both time points. Results AAV patients displayed a significant depletion of all circulating B cell subsets 2-3 months post RTX. In contrast, 2 SLE patients had still detectable numbers of peripheral CD27 ++ CD38 ++ HLA-DR high plasmablasts, CD27 ++ CD38 ++ HLA-DR low plasma cells and CD27 + IgD – memory B cells 8-12 weeks after the RTX infusions (Table 1). BAFF serum levels increased by 70% in AAV (p Conclusions In contrast to patients with SLE, B cell depleting therapy goes along with a significant decline of all B cell subsets in patients with AAV. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.2226