EWRR abstracts Ann Rheum Dis 2011;70(Suppl 2):A1–A94A26 A61 TRIGGERING OF VIRAL RNA SENSORS INDUCES CD55 EXPRESSION ON SYNOVIAL FIBROBLASTS

factor) is a complement-regulatory protein, which is highly expressed by fi broblast-like synoviocytes (FLS). CD55 is also a ligand for CD97, an adhesion-type G protein-coupled receptor abundantly present on leucocytes. We recently showed that lack of either CD55 or CD97 ameliorates disease in murine collagen-induced and K/BxN serum transfer models of arthri-tis.1 Little is known regarding the regulation of CD55 expres-sion in FLS. We therefore investigated the effect of toll-like receptors ligation and pro-infl ammatory cytokines on CD55 expression. Materials and methods Synovial fi broblasts, obtained from biopsy samples of arthritis patients, were cultured and stim-ulated with cytokines (TNF, IFNγ, IL-1β, IL-6, IFNα) or TLR ligands (LTA, poly (I:C), LPS, imiquimod, CpG). Expression of CD55 was measured by fl ow cytometry using domain-specifi