Zhang LW, et al. - The expression of interleukin-17 (IL-17) in patients with primary Sjögren's syndrome (pSS) was determined using eight databases and the correlation between IL-17 and disease severity was studied. Newcastle-Ottawa Scale criteria were used to assess the risk of bias of the included studies. Forty-five articles were analyzed. Patients with pSS exhibited increased expression of IL-17, this was especially noted among those without immunosuppressive treatment. A correlation was observed between IL-17 level and the disease severity of pSS.