ACR Meeting Abstracts

ACR Meeting Abstracts

Abstract Number: 1536

Clinical Features of Patients with Anti-Neutrophil Cytoplasmic Autoantibodies Targeting Native Myeloperoxidase Antigen

Yuji Yamanishi1, Toshiko Ito-Ihara2, Shigeto Kobayashi3, Peter Y. Shane4, Gary S. Firestein5, Hiroshi Hashimoto6 and Kazuo Suzuki7, 1Division of Rheumatology, Hiroshima Rheumatology Clinic, Hiroshima, Japan, 2Department of Clinical Innovative Medicine, Translational Research Center, Kyoto University Hospital, Kyoto, Japan, 3Department of Internal Medicine, Juntendo University Koshigaya Hospital, Tokyo, Japan, 4Tokyo Medical and Dental University, Tokyo, Japan, 5Div of Rheumatology, UCSD School of Medicine, La Jolla, CA, 6Juntendo Tokyo Koto Geriatric Center, Tokyo, Japan, 7National Institute of Infectious Diseases, Tokyo, Japan

Meeting: 2012 ACR/ARHP Annual Meeting

Keywords: , ,

Session Information

Title: Vasculitis

Session Type: Abstract Submissions (ACR)

Background/Purpose: ANCA is a useful diagnostic marker in systemic vasculitic disorders with small-vessel involvement, but depending on the particular test used the myeloperoxidase (MPO)-ANCA results are variable. Unfortunately, the exact origins of the antigens used in most commercial assays have been confidential. In the present study, we performed a comparative analysis between a novel MPO-ANCA assay that targets the native MPO (nMPO) antigen and commercially available assays using sera of patients with clinical features of ANCA-associated vasculitis (AAV).

Methods: Serum samples from 24 patients strongly suspected of having AAV were tested for the presence of MPO-ANCAs by the novel nMPO-ANCA assay and by other commercial-based MPO-ANCA assays. These results were correlated to indirect immunofluorescence microscopy staining patterns and patient clinical parameters. 

Results: Eighteen out of 24 patients (75%) were positive for nMPO-ANCA compared to 13 out of 24 patients (54%) by one of the most frequently used commercial-based MPO-ANCA ELISA assays in Japan. Interestingly, the patients that tested positive with our nMPO-ANCA assay alone showed clinical features of AAV marked by prolonged fever, polyarthritis, and mild nephritis. The titers of nMPO-ANCA decreased in association with clinical improvement after treatment. 

Conclusion: Our data suggest that a positive nMPO-ANCA result, which identifies antibodies to human native MPO antigen, identifies patients with a subset of patients with AAV and a distinct clinical profile. In addition, the titer appeared to correlate with AAV disease activity. While additional studies in larger patient populations will be needed, the nMPO-ANCA test could have clinical utility in detecting AAV-affected patients who have tested negative using commercially available assays.

Disclosure:

Y. Yamanishi,
None;

T. Ito-Ihara,
None;

S. Kobayashi,
None;

P. Y. Shane,

UCB Japan,

3;

G. S. Firestein,
None;

H. Hashimoto,
None;

K. Suzuki,
None.

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