Background To investigate the association between myositis autoantibodies and clinical subsets of inflammatory myositis in Korean patients. polypeptide (anti-p155/140) (16.3% 8 antibodies were the most common followed by anti-Mi2 (14.3% 7 anti-ARS (12.2% 6 and anti-SRP (2.0% 1 antibodies. All MSAs and anti-p140 and anti-p155/140 antibodies were mutually unique. Anti-p140 (23.7% 9 anti-p155/140 (21.1% 8 and anti-Mi2 (18.4% 3 antibodies were found exclusively in DM patients. Anti-p140 antibody was associated with rapidly progressive interstitial lung disease (ILD) (p = 0.001) with a Rabbit polyclonal to annexinA5. sensitivity of 100.0% (4/4) and a specificity of 85.3% (29/34) in DM patients. Anti-p155/140 antibody was associated with cancer-associated DM (p = 0.009) with a sensitivity of 55.6% (5/9) and a specificity of 89.7% (26/29). Micafungin Sodium Cancer-associated survival was significantly worse when anti-p155/140 antibody was present (19.2 ± 7.6 vs. 65.0 ± 3.5 months p = 0.032). Finally anti-ARS antibodies were associated with stable or slowly progressive ILD in PM and DM Micafungin Sodium patients (p = 0.005). Conclusions Anti-p140 and anti-p155/140 antibodies were commonly found autoantibodies in Korean patients with inflammatory myositis. Despite the lack of clinically amyopathic DM patients in the study subjects a strong association was observed between anti-p140 antibody and rapidly progressive ILD. Anti-p155/140 antibody was associated with cancer-associated myositis and poor survival. Background Polymyositis (PM) and dermatomyositis (DM) are systemic autoimmune diseases in which muscles are the primary target of immune-mediated inflammation. In addition to muscular inflammation and dysfunction the systemic complications of PM and DM involve vessels joints the gastrointestinal tract cardiac tissues and lungs . In particular damage to lung parenchyma which manifests as interstitial lung disease (ILD) and accompanying malignancies are the major prognostic factors that contribute to mortality in PM and DM patients [2 3 On the other hand amyopathic dermatomyositis (ADM) is usually a condition in which the common skin manifestations of DM develop without muscle involvement and it constitutes the clinical spectrum of inflammatory myositis together with PM and DM . Clinically amyopathic dermatomyositis (CADM) is an extended concept of ADM in which no muscle weakness is observed with or without subclinical evidence of muscle Micafungin Sodium inflammation on laboratory electrophysiological and/or radiographic evaluations . Treatment-resistant rapidly progressive interstitial lung disease (ILD) has been reported to cluster in ADM/CADM patients [5-7] and appreciable clinical significance has been conferred upon ADM and/or CADM (ADM/CADM). As in other connective tissue diseases PM and DM are characterized by autoantibodies to various cellular components. Some of these autoantibodies are found specifically in PM and DM patients (referred to as myositis-specific autoantibodies MSAs) Micafungin Sodium or in myositis overlap syndrome patients (myositis-associated autoantibodies MAAs). The MSAs tend to be mutually exclusive and are associated with certain clinical subsets  which renders MSAs as useful tools to classify clinical subgroups. The most striking association found Micafungin Sodium to date concerns the association between anti-aminoacyl-tRNA synthetase (anti-ARS) antibodies and the presence of ILD . In recent years novel autoantibodies have been identified in inflammatory myositis such as anti-140-kDa polypeptide (anti-p140)  and anti-155/140-kDa polypeptide (anti-p155/140) antibodies [10 11 Micafungin Sodium Because these antibodies have yet to be extensively studied in non-myositis populations to assure their specificity for myositis and because the presence of anti-p140 antibodies has been largely limited to CADM patients who do not have clinical muscle symptoms [9 12 13 it may be currently inappropriate to classify anti-p140 and anti-p155/140 antibodies as MSAs. However associations between these novel antibodies and unique clinical subsets have been found in adult inflammatory myositis patients; associations between anti-p140 antibody and CADM-associated ILD [9 12 13 and between anti-p155/140 antibody and cancer-associated myositis are such examples [10-12 14 The clinical usefulness of these autoantibodies has well been recognized as diagnostic markers that could potentially alter disease outcomes by facilitating early diagnosis and treatment. However clinical implications regarding these novel antibodies in adult PM and DM.