POS0005 IN PATIENTS WITH IDIOPATHIC INFLAMMATORY MYOSITIS, MUSCLE-RESTRICTED TCR CLONES SHARE STRUCTURAL FEATURES, WHILE THEIR EXPANSION CORRELATES WITH DISEASE ACTIVITY

Background T cells of different lineages including cytotoxic have been implicated in the pathogenesis idiopathic inflammatory myopathies [1]. However, question whether cell response muscle is reflective peripheral blood remains to be fully answered. Objectives To characterize receptor (TCRβ) repertoire and tissues treatment naïve patients with newly diagnosed (IIMs). Methods High throughput RNA sequencing TCRβ chain was performed tissue twenty newly-diagnosed treatment-naïve IIM healthy controls. Results thereof were correlated markers disease activity. Muscle show more expansion clones decreased diversity when compared as well controls (both p=0.0001). Several expanded are restricted cannot retrieved blood. These significantly longer CDR3 regions (also) found circulation (p=0.0002), while their region hydrophobic (p<0.01). Network analysis shows that clonal TCR signatures shared between patients. Increased increased CK levels (p=0.03), tends correlate strength (p=0.08). Conclusion clusters sequences across Muscle-restricted specific structural features receptor, associated findings indicate responses act key players IIM. Reference [1]Mizuno, K., et al., Oligoclonal circulating tissue-infiltrating CD8+ killer/effector phenotypes juvenile dermatomyositis syndrome. Clin Exp Immunol, 2004. 137 (1): p. 187-94 Acknowledgements: NIL. Disclosure Interests None Declared.