Infliximab treatment was not effective in refractory inflammatory myopathies. In view of radiological and clinical worsening, and activation of the type I IFN system in several cases, infliximab is not an alternative treatment in patients with treatment-resistant myositis.

Objective. To investigate type I interferon (IFN) system activation and its correlation with autoantibodies and organ manifestations in polymyositis (PM), dermatomyositis (DM), and inclusion body myositis.Methods. Sera from 30 patients and 16 healthy controls, or purified IgG, were combined with material released from necrotized cells to stimulate Conclusion. Immune complexes containing antiJo-1 or anti-Ro 52/anti-Ro 60 autoantibodies and RNA may act as endogenous IFN␣ inducers that activate IFN␣ production in PDCs. These PDCs could be of importance for inducing myositis, whereas in DM patients without autoantibodies the presence of MX-1 protein in capillaries suggests another cellular IFN␣ source and induction mechanism. Consequently, the type I IFN system may be of importance in both PM and DM, but via different pathways.The idiopathic inflammatory myopathies polymyositis (PM), dermatomyositis (DM), and inclusion body myositis (IBM) are characterized by symmetric, proximal muscle weakness and decreased muscle endurance. Other organs are frequently involved, such as skin in DM and lungs in PM and DM. Shared classic histopathologic features are the presence of inflammatory cell infiltrates in skeletal muscle tissue, dominated by T cells and macrophages, and regenerating and degenerating muscle fibers (1). Another characteristic feature is the presence of autoantibodies, of which anti-histidyltransfer RNA synthetase (anti-HisRS or anti-Jo-1) is one of the most frequent (2). This autoantibody is considered myositis specific and is associated with a distinctive clinical phenotype, the so-called antisynthetase syndrome, which is characterized by myositis, Raynaud's phenomenon, interstitial lung disease (ILD),

Our finding of elevated serum levels of BAFF in patients with myositis with described phenotypes together with the correlations between levels of BAFF and CK and a negative correlation with dose of glucocorticoids, indicate that BAFF could be a potential therapeutic target in such cases.