Purpose of review: Idiopathic inflammatory myopathy is characterized by the production of autoantibodies to various cellular constituents. These autoantibodies closely correlate with certain clinical conditions and prognosis of disease. This review examines recent progress in myositis-specific autoantibodies, particularly in their clinical significance and pathophysiological roles.
Recent findings: During the 1-year review period, novel myositis-specific autoantibodies were identified in clinically amyopathic dermatomyositis (anti-CADM-140 antibody) and malignancy-associated myositis (anti-p155 and anti-p155/p140 antibodies). These new autoantibodies are extremely important because it is thought that myositis-specific autoantibodies are negative in these subgroups, and may enable a new classification of idiopathic inflammatory myopathy. New clinical aspects of other myositis-specific autoantibodies (anti-aminoacyl-tRNA synthetases, anti-signal recognition particles and anti-Mi-2) are also described. The possibility was raised that the high expression of myositis-specific autoantigens in regenerating muscle cells and certain cancers may be involved in initiating and perpetuating the autoimmune response in myositis.
Summary: Myositis-specific autoantibodies are useful markers for clinical diagnosis, classification and predicting prognosis of idiopathic inflammatory myopathy. To understand the etiopathogenic mechanisms of the disease it is particularly important to elucidate the nature of target autoantigens recognized by these myositis-specific autoantibodies.