[Pathophysiology and Laboratory Findings in Patients with ANCA-Associated Vasculitis]

Pathophysiological features and laboratory findings in patients with anti-neutrophil cytoplasmic antibody (ANCA) -associated vasculitis are described. In contrast to Western countries, MPO-ANCA-positive microscopic polyangiitis and renal-limited vasculitis is the most common form of ANCA-associated vasculitis in Japanese patients. Oral prednisolone in combination with immunosuppressive agents has improved patient survival in older Japanese patients. However, the recurrence rate has significantly increased in recent years Accumulative evidence supports a direct pathogenic role of ANCA in glomerulonephritis and vasculitis, in which inflammatory processes with the up-regulation of cytokines/chemokines and possible involvement of a neutrophil extracellular trap may play a role. However, whether or not the measurement of ANCA titers reflects disease activity and predicts the onset and/or relapse of ANCA-associated vasculitis remains controversial. Further studies will be required to determine the clinical significance of ANCA in more detail. In addition to ANCA, measurements of novel clinical test items, including anti-erythropoietin receptor antibody, may reveal the possibility of their application as useful biomarkers of the pathophysiology and clinical manifestations in patients with ANCA-associated vasculitis.