A possible mechanism contributing to the increase of PR3+ B cells in patients with MPO-AAV might be a nonspecific defect in clonal anergy predisposing to autoimmunity (30), because levels of the circulating PR3 antigen are increased in patients with both PR3-AAV and MPO-AAV compared with HCs as a consequence of neutrophil activation. This evidence concerns the gene MPO and Autoimmunity.