Objective Myositis-specific autoantibodies (MSAs) are useful tools for identifying clinical subsets of patients with idiopathic inflammatory myopathies (IIMs). There have been few reports on antibodies to some DNA mismatch repair enzymes (MMREs) in patients with IIMs. This study was undertaken to determine the frequencies and clinical associations of antibodies to 7 types of MMREs (MLH1, MLH3, MSH2, MSH3, MSH6, PMS1, and PMS2) in patients with IIMs and other systemic autoimmune diseases.
Methods Clinical data and serum samples were collected from 239 Japanese patients with IIMs (147 with adult dermatomyositis, 13 with juvenile dermatomyositis, 57 with polymyositis, and 22 with myositis overlap syndrome). One hundred patients with other diseases, including 40 with systemic lupus erythematosus (SLE), were assessed as disease controls. The presence of anti-MMRE antibodies in serum was examined by immunoprecipitation, enzyme-linked immunosorbent assay, and immunoprecipitation/Western blotting.
Results Anti-MMRE antibodies were found in 15 patients with IIMs and 3 patients with SLE. They were restricted to MLH1, PMS1, MSH2, and PMS2, with simultaneous positivity for more than one of these antibodies occurring in some patients. Nine IIM patients with anti-MMREs also had other MSAs and their associated clinical features. All patients with anti-MMREs were still living at the time of the present analysis.
Conclusion Anti-MMRE antibodies, which often coexist with other MSAs, may be serologic markers for good prognosis in IIMs.
All Science Journal Classification (ASJC) codes
- Immunology and Allergy