Inclusion Criteria:  meet the PM/DM diagnostic criteria according to Bohan-Peter consistent with ILD diagnosis predicted forced vital capacity (FVC) of at least 50% patients who did not use immunosuppress agents (including but not limited to cyclophosphamide, cyclosporine, leflunomide, azathioprine, tacrolimus, etc.) at the time of screening, or who had stopped taking drugs for ≥3 months.  Exclusion Criteria:  Anti MDA5 antibody positive DM and necrotizing myopathy patients if they had other connective tissue diseases, an underlying cancer, a concomitant active infection.