Clinical features of patients with anti-neutrophil cytoplasmic autoantibodies targeting native myeloperoxidase antigen.

Abstract

OBJECTIVES:

Anti-neutrophil cytoplasmic autoantibodies (ANCA) are useful diagnostic markers in systemic vasculitic disorders with small-vessel involvement, but depending on the particular test used, the myeloperoxidase (MPO)-ANCA results are variable. In the present study, we performed a comparative analysis between our originally developed nMPO-ANCA assay that targets the native MPO antigen and other commercially available assays using sera of patients with clinical features of ANCA-associated vasculitis (AAV).

METHODS:

Sera of 24 patients strongly suspected of having AAV were examined for the presence of MPO-ANCAs by our 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 with 13 out of 24 patients (54 %) by one of the most frequently used commercial-based MPO-ANCA enzyme-linked immunosorbent assays (ELISAs) in Japan. Interestingly, the patients who tested positive with our nMPO-ANCA assay alone showed clinical features of AAV marked by continuous fever, polyarthritis, and mild nephritis. The titers of nMPO-ANCA decreased in association with clinical improvement after treatment.

CONCLUSIONS:

Our data suggest that a positive nMPO-ANCA result, which identifies antibodies to human native MPO antigen, correlates with AAV disease activity. Moreover, the nMPO-ANCA test has clinical utility in detecting AAV-affected patients who have tested negative using commercially available assays.

• Authors: Yuji Yamanishi, Toshiko Ito-Ihara, Tomokazu Nagao, Kazuko Uno, Shigeto Kobayashi, Eri Muso, Peter Y Shane, Gary S Firestein, Hiroshi Hashimoto, Tomio Okazaki, Kazuo Suzuki
• Journal: Modern rheumatology (Mod Rheumatol) Vol. 23 Issue 5 Pg. 963-71 (Sep 2013) ISSN: 1439-7609 [Electronic] England
• PMID: 23085883 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Antineutrophil Cytoplasmic
• Ferrous Compounds
• Maleimides
• Metallocenes
• N-(2-ferrocene-ethyl)maleimide
• Peroxidase

Topics

• Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis (diagnosis, immunology)
• Antibodies, Antineutrophil Cytoplasmic (blood, immunology)
• Enzyme-Linked Immunosorbent Assay
• Ferrous Compounds
• Humans
• Maleimides
• Metallocenes
• Peroxidase (immunology)
• Sensitivity and Specificity