D-penicillamine and polymyositis: the significance of the anti-Jo-1 antibody.

A 57-yr-old lady developed polymyositis whilst taking D-penicillamine for RA. D-Penicillamine-induced polymyositis occurs in RA with a greater frequency than idiopathic polymyositis. Anti-acetyl choline receptor antibodies and ANA were positive, consistent with drug-induced disease. Anti-Jo-1 antibodies are considered specific for idiopathic myositis, and their presence was unexpected. Following withdrawal of the drug, the disappearance of the anti-Jo-1 and other antibodies coincident with clinical improvement, suggested that D-penicillamine was responsible for inducing antibody production.