Anti-PL-12 antibody (anti-alanyl-tRNA synthetase antibody) is one of the antisynthetases; an association of anti-PL12 antibody with a high frequency of interstitial lung disease, myosistis, arthritis, skin rash, Raynaud’s phenomenon, and fever has been reported, although the number of patients described in such reports was limited.

Autoantibodies to aminoacyl-tRNA synthetases (anti-synthetases) are found in 30% of sera from patients with myositis, being highly specific for this disorder and strongly associated with complicating interstitial lung disease.

So far, autoantibodies recognizing five different synthetases have been described: anti-Jo-1 (histidine), anti-PL-12 (alanine), anti-PL-7 (threonine), anti-EJ (glycine) and anti-OJ (isoleucine).