Relationship between the level of interleukin-9 expression in serum of connective tissue disease patients with interstitial lung disease

Objective To investigate the level of interleukin (IL) -9 in patients with connective tissue disease (CTD) and connective tissue disease with interstitial lung disease (CTD-ILD) ,and explore the role of IL-9 in the pathogenesis of CTD and CTD-ILD.Methods Sixty-one hospitalized untreated CTD patients were recruited and 20healthy volunteers were enrolled as healthy controls.Patients in the CTD group included 19 systemic sclerosis (SSc) patients,15 rheumatoid arthritis (RA) patients,