Which myositis-specific antibody is associated with polymyositis and dermatomyositis and may relate to interstitial lung disease?

• A. Anti-Jo-1
• B. Anti-Smith
• C. Anti-dsDNA
• D. Anti-RNP

Answer: (A)

In PM/DM, certain myositis-specific antibodies help connect muscle inflammation with other organ involvement, and the classic antisynthetase antibody is Anti-Jo-1. This antibody targets histidyl-tRNA synthetase and defines antisynthetase syndrome, which commonly features polymyositis or dermatomyositis plus interstitial lung disease, along with arthritis, mechanic’s hands, and Raynaud’s phenomenon. That combination makes Anti-Jo-1 the best fit for PM/DM with a potential link to ILD.

The other antibodies are associated with different diseases: Anti-Smith is most characteristic of systemic lupus erythematosus; Anti-dsDNA is also a hallmark of SLE; Anti-RNP is often seen in mixed connective tissue disease. While these antibodies indicate other autoimmune processes, they do not specifically point to PM/DM with interstitial lung disease.