[Anti-Jo-1 antibodies: specific autoantibodies for polymyositis with interstitial pulmonary fibrosis. 2 case reports].

Anti-Jo-1 antibodies are rare autoantibodies, which bind and inhibit the activity of histidyl-tRNA-synthetase. They are predominantly found in a genetically and clinically distinct subset of myositis patients, presenting with interstitial alveolitis. We describe the case of a 22-year-old woman with Jo-1-syndrome with typical features of myositis, pulmonary fibrosis, nonerosive symmetric polyarthritis, Gottron's papules at the metacarpophalangeal joints and classic heliotrope discoloration of the periorbital area with edema. The patient did not respond to chloroquine, azathioprine, intravenous immunoglobulins or cyclophosphamide. Remission was finally achieved with oral methotrexate plus corticosteroids. The second case describes a 34-year-old man with myositis, who rapidly developed respiratory insufficiency after suffering from joint pain and stiffness for about 10 weeks. He responded well to cyclophosphamide pulse therapy and high-dose corticosteroids. The second case demonstrates that control of the interstitial alveolitis is most important for long-term outcome. Therefore, immunosuppressive drugs should be used along with corticosteroids as early as possible.