TY - JOUR T1 - Disease specificity of autoantibodies to cytosolic 5′-nucleotidase 1A in sporadic inclusion body myositis versus known autoimmune diseases JF - Annals of the Rheumatic Diseases JO - Ann Rheum Dis SP - 696 LP - 701 DO - 10.1136/annrheumdis-2014-206691 VL - 75 IS - 4 AU - Megan K Herbert AU - Judith Stammen-Vogelzangs AU - Marcel M Verbeek AU - Anke Rietveld AU - Ingrid E Lundberg AU - Hector Chinoy AU - Janine A Lamb AU - Robert G Cooper AU - Mark Roberts AU - Umesh A Badrising AU - Jan L De Bleecker AU - Pedro M Machado AU - Michael G Hanna AU - Lenka Plestilova AU - Jiri Vencovsky AU - Baziel G van Engelen AU - Ger J M Pruijn Y1 - 2016/04/01 UR - http://ard.bmj.com/content/75/4/696.abstract N2 - Objectives The diagnosis of inclusion body myositis (IBM) can be challenging as it can be difficult to clinically distinguish from other forms of myositis, particularly polymyositis (PM). Recent studies have shown frequent presence of autoantibodies directed against cytosolic 5′-nucleotidase 1A (cN-1A) in patients with IBM. We therefore, examined the autoantigenicity and disease specificity of major epitopes of cN-1A in patients with sporadic IBM compared with healthy and disease controls.Methods Serum samples obtained from patients with IBM (n=238), PM and dermatomyositis (DM) (n=185), other autoimmune diseases (n=246), other neuromuscular diseases (n=93) and healthy controls (n=35) were analysed for the presence of autoantibodies using immunodominant cN-1A peptide ELISAs.Results Autoantibodies directed against major epitopes of cN-1A were frequent in patients with IBM (37%) but not in PM, DM or non-autoimmune neuromuscular diseases (<5%). Anti-cN-1A reactivity was also observed in some other autoimmune diseases, particularly Sjögren's syndrome (SjS; 36%) and systemic lupus erythematosus (SLE; 20%).Conclusions In summary, we found frequent anti-cN-1A autoantibodies in sera from patients with IBM. Heterogeneity in reactivity with the three immunodominant epitopes indicates that serological assays should not be limited to a distinct epitope region. The similar reactivities observed for SjS and SLE demonstrate the need to further investigate whether distinct IBM-specific epitopes exist. ER -