RT Journal Article SR Electronic T1 Elevated Serum Levels of Soluble CD163 in Polymyositis and Dermatomyositis: Associated with Macrophage Infiltration in Muscle Tissue JF The Journal of Rheumatology JO J Rheumatol FD The Journal of Rheumatology SP jrheum.141307 DO 10.3899/jrheum.141307 A1 Qing-Lin Peng A1 Yin-Li Zhang A1 Xiao-Ming Shu A1 Han-Bo Yang A1 Lu Zhang A1 Fang Chen A1 Xin Lu A1 Guo-Chun Wang YR 2015 UL http://www.jrheum.org/content/early/2015/04/09/jrheum.141307.abstract AB Objective To investigate serum levels of soluble CD163 (sCD163) in patients with polymyositis (PM) and dermatomyositis (DM), and to correlate these to clinical manifestations and laboratory data. Methods Serum levels of sCD163 were detected in 24 patients with PM, 84 patients with DM, and 46 healthy controls by using the ELISA method. Immunohistochemistry staining of macrophage infiltration in muscle tissue using anti-CD163 monoclonal antibody was conducted on muscle biopsy specimens from 13 patients with PM and 17 with DM. Results Serum levels of sCD163 were significantly increased in patients compared with healthy controls (p < 0.001). Patients with interstitial lung disease (ILD) had statistically higher sCD163 levels than patients without ILD (p < 0.001). High serum sCD163 levels were associated with increased incidence of antinuclear antibody (p < 0.05), higher serum levels of immunoglobulin G (p < 0.01) and immunoglobulin A (p < 0.05), and increased erythrocyte sedimentation rates (p < 0.01). Serum sCD163 levels were inversely correlated with CD3+ T cell counts in peripheral blood of patients (r = –0.306, p < 0.01). Cross-sectional assessment and longitudinal study revealed a significant correlation between serum sCD163 levels and disease activity. Patients with high serum sCD163 levels showed a higher incidence of CD163+ macrophage infiltration in muscle tissue than patients with normal sCD163 levels (chi-square value = 10.804, p < 0.01). Conclusion Serum levels of sCD163 were significantly elevated and correlated with disease severity in patients with PM/DM, suggesting serum sCD163 as a promising biomarker in the disease evaluation of PM/DM. Our finding of elevated serum sCD163 levels associated with muscle macrophage infiltration highlights the role activated macrophage plays in the pathogenesis of PM/DM.