IL17A and systemic lupus erythematosus: Several studies have shown that IL-17 levels are altered in patients with SLE and that the levels of IL-17 produced in the plasma and target organs are positively linked with disease severity.202,203 Interestingly, in two animal models of lupus, decreased IL-17 expression effectively alleviated the pathological changes in SLE.204 However, the correlation between IL-17 levels and SLE severity remains unclear.