Myositis autoantibodies in Iranian myositis patients: assessment the frequency and clinical relevancy.

INTRODUCTION

Dermatomyositis (DM) and polymyositis (PM) are known as two major types of idiopathic inflammatory myopathies (IMMs). During the past years, growing data strongly suggest the clinical significance of myositis-associated autoantibodies (MAAs) and myositis-specific autoantibodies (MSAs). The present study aimed to determine the profile of MSAs and MAAs, subsequently to address the clinical significance of these autoantibodies in Iranian myositis patients.

METHODOLOGY

In this cross-sectional study, 28 DM and 24 PM patients were entered. Demographic and clinical characteristics were collected by direct examination and patients' medical record. The existence of MSAs and MAAs was assessed by indirect immunofluorescence then using immunoblotting (FA 1510-1005-1, DL 1530-1601-4 G; Euroimmun, Germany). Data were analyzed using the SPSS software (v22; SPSS Inc. Chicago, IL, USA).

RESULTS

The mean age of the patients was 46.18 ± 12.95 years and male/female ratio was 28.8/71.2. Autoantibodies were positive in 63.46% of myositis patients. Interestingly, anti-TIF1γ and anti-PL7 were significantly associated with malignancy (P < 0.001, P = 0.008; respectively). The existence of autoantibody and anti-Jo1 had significant relation with interstitial lung disease (ILD) (P = 0.034, P = 0.006; respectively). Joint involvements including arthritis and arthralgia were significantly associated with anti-Ro52 and anti-Jo1 (P = 0.04, P = 0.02; respectively).

CONCLUSION

Taken together, it can be concluded that certain myositis autoantibodies present clinical significance which is in line with the literature. The use of these autoantibodies as biomarkers by line blotting along with indirect immunofluorescence facilitates diagnosis of inflammatory myopathies and makes it more accurate as well as better management of myositis patients if used based on a science-based manner. Key Points • Identification of MSAs and MAAs facilitates the diagnosis of inflammatory myopathies and provides better myositis patient's management if used according to a science-based manner. • Anti-rod and ring antibody was detected in a patient with ovarian cancer-induced dermatomyositis. • Malignancy and ILD are integrated parts of myositis which can be associated with MSAs and MAAs.