Purpose of review-To review
autoantibodies associated with different subtypes of
idiopathic inflammatory myopathy (IIM) and their clinical applications. IIM are a heterogenous group of autoimmune disorders characterized by
muscle weakness, cutaneous features, and internal organ involvement. The diagnosis and classification, which is often challenging, is made using a combination of clinical features, muscle
enzyme levels, imaging, and biopsy. The landmark discoveries of novel
autoantibodies specific to IIM subtypes have been one of the greatest advancements in the field of
myositis. The specificity of these
autoantibodies has simplified the diagnostic algorithm of IIM with their heterogenous presentation and outdated the earlier diagnostic criteria.
Myositis-specific
antibodies (MSAs) have improved diagnostics, clinical phenotyping, and prognostic stratification of the subtypes of IIMs. Furthermore, the levels of certain MSAs correlate with disease activity and muscle
enzyme levels such that titers may be able to be used to predict disease course and treatment response.