Objective:To explore the role of NETs in dermatomyositis associated interstitial lung disease(ILD)and to analyse the association between NETs and anti-MDA5 antibody.Methods:Patients with clinically amyopathic dermatomyositis(CADM,n=20),classic dermatomyositis(cDM,n=30),polymyositis(PM,n=20)and normal controls(n=20)were enrolled in our study.Serum NETs concentrations were assessed by Pico Green dsDNA Quantitation Kits.Anti-MDA5 antibody and KL-6 levels were detected by enzyme-linked immunosorbent assay.Immunofluorescent staining was used to determine NETs formation.Phorbol 12-myristate 13-acetate(PMA),5%autologous serum(AS)and culture medium were applied to stimulate peripheral neutrophils.