The Role of Autoantibodies in Idiopathic Inflammatory Myopathies

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of autoimmune muscle diseases with systemic involvement. Patients with IIM present with varying degrees of muscle disease, cutaneous manifestations, and internal organ involvement. The diagnosis and classification of IIM is based primarily on the classification system composed of clinical features, laboratory value and muscle biopsy. In addition, the identification and characterization of myositis-related autoantibodies can help diagnosis and classification. Recently, many studies have also demonstrated that the physician can define the clinical syndromes, establish treatment strategy and predict outcomes based on the patients’ myositis-specific autoantibodies (MSA) and myositis-associated antibodies (MAA) profiles. MSAs are found exclusively in IIMs and facilitate the identification of subsets of patients with relatively homogeneous clinical features. MAAs are frequently found in association with other MSA; however, they may also be detected in various connective diseases. (J Rheum Dis 2019;26:165-178)