Diagnostic importance of anti-proteasome antibodies

20S proteasome represents the proteolytic core complex for cytoplasmic prot ein degradation that is involved in the activation and regulation of the im mune response, in this context, proteasome generates antigenic peptides for the MHC class I pathway and activates NF-kappa B. In a recent analysis, we could identify a frequent humoral autoimmune response directed against spe cific proteasomal subunits in patients with autoimmune myositis, systemic l upus erythematosus and primary Sjogren's syndrome. The outer ring subunit H C9(alpha 3) was identified as the predominant target of the anti-proteasome response in these entities. In addition to the reactivity against HC9(alph a 3), patients with primary Sjogren's syndrome expressed a more polyspecifi c recognition pattern of proteasomal subunits involving the active inner ri ng proteins. in follow-up analysis, anti-proteasome antibody titers reveale d a correlation with disease activity in patients with autoimmune myositis and systemic lupus erythematosus. The current review summarizes recent data providing evidence that the 20S proteasome represents an important target of the humoral autoimmune response in systemic autoimmune diseases and exte nds insight into pathogenic aspects of these diseases. Copyright(C) 2000 S. Karger AG,Basel.