Effectiveness of plasmapheresis in ANCA clearance in patients with ANCA-associated vasculitides.

Introduction: Plasmapheresis is a therapeutic method based on removal of high molecular weight particles from blood. It is used in a variety of clinical entities in which pathogenic role of such particles has been proven e.g. ANCA-associated vasculitides (granulomatosis with polyangiitis [GPA] and microscopic polyangiitis [MPA]). Efficacy of plasmapheresis in ANCA antibodies removal and its impact on disease activity has not been adequately investigated so far. Influence of antibodies levels on disease activity also remains unknown. Objectives: Analysis of plasmapheresis effect on serum ANCA levels in patients with ANCA-associated vasculitides. Patients and methods: Seven patients with diagnoses of ANCA-associated vasculitides were enrolled in the study between November 2015 and April 2016. All of them underwent plasmapheresis procedures. Serum ANCA levels were measured before and after plasmaphereses using fluoroimmunoenzymatic assay (FEIA). Disease activity was assessed using Birmingham Activity Vasculitis Score; BVAS ver. 3 before first plasma exchange procedure. Results: Patients in disease exacerbation (BVAS 5-10) with positive ANCA antibodies were enrolled in the study: 2 patients with GPA and 5 patients with MPA. Number of performed plasmapheresis procedures ranged from 5 to 7 (median=7). Decrease of serum antibodies concentration was observed in all patients (mean decrease of 88.3% (±10.1%)) with statistically significant difference in mean antibodies concentration before and after plasmapheresis procedures (113.0 vs 15.4; p=0.014). Conclusions: Plasmapheresis is an effective method of ANCA antibodies removal in patients in disease exacerbation.