IL21 and systemic lupus erythematosus: In our present study, based on mice models, we found that GDF-15 alleviated lupus by reducing renal damage (Figure 4), reversing CD8+, CD19+, and TH2 cells dysregulation (Figure 5), inhibiting production of IL-1β, IL-2, IL-4, IL-21, IL-22 (Figure 6), ANA, and total IgG (Figure 7).