A Case of ANCA-Associated Vasculitis with Positive PR3 and MPO Antibodies

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of autoimmune diseases including granulomatous polyvasculitis (GPA), microscopic polyvasculitis (MPA), and eosinophilic granulomatous polyvasculitis (EGPA). The main antigens ANCA targets are protease 3 (PR3) and myeloperoxidase (MPO). PR3-ANCA is mainly related to GPA, while MPO-ANCA is related to MPA. The presence of these antibodies is critical to the diagnosis of AAV.

A case of ANCA-associated vasculitis with PR3 and MPO antibody positive due to PTU was reported.

After the patients stopped PTU, PR3 antibody gradually decreased to negative, MPO antibody was relatively stable, and the fluorescent karyotype was p-ANCA. The positive PR3 antibody in this patient was considered to be related to PTU.

ANCA, anti-PR3 antibody, and anti-MPO antibody are closely related to systemic vasculitis and are affected by many factors. Abnormal results in clinical work should be reviewed immediately and communicated with clinicians to avoid adverse consequences.