Comparison of radioimmunoprecipitation versus antigen-specific assays for identification of myositis-specific autoantibodies in dermatomyositis patients

Abstract

Background. To confirm the antigen specificities of autoantibodies that precipitate 140-kDa (anti-p140) or 155/140-kDa polypeptides (anti-p155/140) previously identified by radioimmunoprecipitation in Korean patients with dermatomyositis (DM) and to look into the relationship between each MSA and clinical features of DM.

Methods. Seventeen serum samples of classic DM patients who had been found to have either anti-p140 antibodies (n = 9) or anti-p155/140 (n = 8) antibodies in our previous study 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. Two out of nine had anti-MJ/NXP-2 antibodies with no interstitial lung disease (ILD). All eight anti-p155/140 antibody positive patients were found to have anti-TIF-1γ antibodies. 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. The associations between anti-MDA5 antibody and rapidly progressive ILD and between anti-TIF-1γ antibody and cancer-associated DM were confirmed to be significant.

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

Keywords:

• antibody specificities
• autoantibodies
• myositis

Acknowledgments

This work was supported by the MKE/KEIT R&D Program (Grant No. 10035615) and the World Class University program of MEST and the NRF (Grant No. R31-2008-000-10103-0).

Conflict of interests

None.

Author's contributions

EHK was involved in the acquisition and analysis of clinical data and drafted the manuscript. MK and YO carried out the antibody detection assays. EYL, YJL, and EBL helped clinical data acquisition. EHK and YWS were involved in the concept and design of the work. All authors have read and approved the final manuscript.