Objective To detect anti-clinically amyopathic dermatomyositis (CADM)-140 antibody in patients with dermatomyositis (DM) or CADM,and to estimate its clinical correlation.Methods Serum samples were collected from 22 patients with DM,16 patients with CADM,46 patients with other connective tissue diseases complicated by interstitial lung disease(including 8 cases of polymyositis,15 cases of systemic lupus erythematosus,5 cases of systemic sclerosis,6 cases of Sj(o)gren syndrome,6 cases of mixed connective tissue disease,6 cases of idiopathic pulmonary fibrosis),and 5 normal human controls.Enzyme-linked immunosorbent assay (ELISA) was performed with the recombinant melanoma differentiation-associated gene 5(rMDA)as a substrate to measure the anti-CADM-140 antibody in these serum samples.Clinical manifestations were compared between patients with anti-CADM-140 antibody and those without.Results The anti-CADM-140antibody was found in 43.8% (7/16) of patients with CADM and 9.1%(2/22) of patients with DM(P<0.05),but absent in the patients with other connective tissue diseases and in the normal human controls.A significant incroase was observed in anti-CADM-140 antibody-positive patients with DM/CADM in the incidence of cutaneous ulceration and necrosis,interstitial lung disease and rapidly progressive interstitial lung disease (8/9 vs.6.9%,P<0.01;9/9 vs.48.3%,P<0.01;5/9 vs.0,P<0.05),serum lactate dehydrogenase level(328.3±104.2 vs 241.1±100.3 IU/L P<0.05),erythrocyte sedimentation rate(40.8±23.1 vs.22.5±16.8 mm/1 h,P<0.05),high resolution computed tomography score(122.9±54.8 vs.70.0±59.8,P<0.05)compared with anti-CADM-140 antibody-negative patients with DM/CADM.The ereatine kinase level was significantly lower(156.3±260.8 vs.1806.2±3737.1 IU/L P<0.05)in anti-CADM-140 antibody-positive patients with DM/CADM than in anti-CADM-140 antibody-negative patients with DM/CADM,while no significant difference was noted in the positivity rate of antinuclear antibodies or incidence of malignancies between the antibody-positive and-negative patients with DM/CADM.Conclusions Anti-CADM.140 antibody not only is useful for the diagnosis of interstitial lung disease in patients with DM/CADM,but also may serve as a serum marker for rapidly progressive interstitial lung disease.Monitoring of serum anti-CADM-140 antibody might help to predict the progression of interstitial lung disease in patients with DM/CADM.