Comparison Of Radioimmunoprecipitation Versus Antigen Specific Assays For Identification Of Myositis Specific Autoantibodies In Dermatomyositis Patients

Eun Ha Kang¹, Eun Young Lee², Yun Jong Lee³, Eun Bong Lee⁴ and Yeong Wook Song⁵, ¹Internal Medicine, Rheumatology, Seoul National University Bundang Hospital, Seongnam-si, South Korea, ²Internal medicine, Division of Rheumatology, Department of Internal Medicine, Seoul National University, Seoul, South Korea, ³Division of Rheumatology, Department of Internal Medicine, Rheumatology, Seoul National University, Seoul, South Korea, ⁴Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea, ⁵Division of Rheumatology, Department of Internal Medicine, Seoul National University, Seoul, South Korea

Meeting: 2013 ACR/ARHP Annual Meeting

Keywords: Autoantibodies and myositis

Session Information

Title: Muscle Biology, Myositis and Myopathies: Advances in the Epidemiology, Immunology and Therapy of Myositis

Session Type: Abstract Submissions (ACR)

Background/Purpose: To confirm the antigen specificities of autoantibodies that precipitate 140 kDa (anti-p140) or 155/140 kDa polypeptides (anti-p155/140) on radioimmunoprecipitation (RIP) in Korean patients with dermatomyositis (DM).

Methods: Forty nine sera from patients who had been diagnosed as having inflammatory myopathy according to Bohan and Peter criteria were examined using RIP. Subsequently, 17 serum samples of DM patients who were found to have either anti-p140 (n = 9) or anti-p155/140 antibodies (n = 8) were examined using enzyme-linked immunosorbent assay (for anti-MDA5 antibodies) and immunoblotting (for anti-MJ/NXP-2 and anti-TIF-1γ antibodies).

Results: Seven out of nine anti-p140 antibody positive patients were found to have anti-MDA5 antibodies. The rest two had anti-MJ/NXP-2 antibodies with no interstitial lung disease (ILD). The association of anti-MDA5 antibody with rapidly progressive ILD was found to be significant (4/8 vs. 0/41, p = 0.0003). All eight anti-p155/140 antibody positive patients were found to have anti-TIF-1γ antibodies, showing a significant association between anti-TIF-1γ antibody and cancer-associated DM (5/8 vs. 6/41, p = 0.009). Anti-TIF-1γ and anti-MDA5 antibodies were simultaneously detected in one patient with anti-p155/140 antibody, who suffered HIV infection and non-Hodgkin’s lymphoma.

Conclusion: Although radioimmunoprecipitation still looks to be a good screening tool, confirmation with antigen-specific assays seems mandatory. The associations between anti-MDA5 antibody and rapidly progressive ILD and between anti-TIF-1γ antibody and cancer-associated DM were confirmed in Korean patients with DM.

Disclosure:

E. H. Kang,
None;

E. Y. Lee,
None;

Y. J. Lee,
None;

E. B. Lee,
None;

Y. W. Song,
None.

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