Researchers from Okayama University have reported that monitoring a particular antigen can enable clinicians to predict relapse of patients with the vascular disease antineutrophil cytoplasmic antibody (ANCA) -associated vasculitis (AAV).1

AAV refers to a set of diseases—eosinophilic granulomatosis with polyangiitis, granulomatosis with polyangiitis, and microscopic polyangiitis—the characteristics of which are inflammation and destruction of small blood vessels. Clinical signs vary and different organs can be affected, including the kidneys, lungs, and stomach.

Antibodies are molecules produced by the immune system to counteract bacteria and viruses. When a bacterial or viral pathogenic molecule (an antigen) is detected, an antibody neutralizes it by binding to it. However, autoantibodies are sometimes produced against the body’s own proteins, and can cause autoimmune diseases.

The autoantibody known as antineutrophil cytoplasmic antibody (ANCA) can be triggered by at least two antigens, proteinase 3 (PR3) and myeloperoxidase (MPO), causing ANCA-associated vasculitis.

Together with their colleagues, Haruki Watanabe, MD, an assistant professor, and Ken-Ei Sada, MD, PhD, an associate professor, both in the Okayama University department of medicine and clinical science, investigated whether MPO-ANCA can be used as a biomarker for the relapse of AAV. The researchers’ findings suggest that monitoring MPO-ANCA levels may be useful for predicting relapse in patients with AAV.

The researchers looked at data for 271 MPO-ANCA-positive patients who had achieved remission of AAV within 6 months after therapy was started. Levels of MPO-ANCA were measured several times during a 2-year period. The researchers found that for 72% of the patients, MPO-ANCA levels decreased to normal within 6 months after therapy began.

For 40% of the patients with complete follow-up data, however, MPO-ANCA later reappeared. Such reappearance was associated with a relapse of AAV, occurring simultaneously or later. The researchers concluded that reappearance of MPO-ANCA is a promising marker for AAV relapse.

The research team also found indications that MPO-ANCA reappearance could be particularly useful as a biomarker for relapse of AAV with kidney involvement (renal AAV), since only four of the study’s patients without renal involvement experienced relapse. However, a larger study would be necessary to establish a link between MPO-ANCA reappearance and relapse of non-renal AAV.

The researchers point out that their study has some limitations: the data were obtained earlier, in the context of other investigations, and different participating institutions used different analytic procedures for qualitatively assessing ANCA content. Nevertheless, the study was the largest of its kind so far, and also the first with case-control analysis.

Watanabe and colleagues conclude that for patients who have recovered from MPO-AAV, routine MPO-ANCA monitoring should be implemented to predict possible relapse.


  1. Watanabe H, Sada KE, Matsumoto Y, et al. Association between reappearance of myeloperoxidase-antineutrophil cytoplasmic antibody and relapse in antineutrophil cytoplasmic antibody-associated vasculitis: subgroup analysis of nationwide prospective cohort studies. Arthritis Rheumatol. 2018;70(10):1626–1633; doi: 10.1002/art.40538.

Featured image: Workflow and characteristics of patients involved in the MPO-ANCA biomarker study at Okayama University.