IL-21 induces the production of IgG1 and IgG3 in B-cells. IL-21 may promote the transition between innate and adaptive immunity. IL-21 may have a role in proliferation and maturation of natural killer cells in synergy with IL15. IL-21 stimulates interferon gamma production in T-cells and natural killer cells by synergy with IL15 and IL18. Dysregulation of IL-21 has a role in multiple immune-mediated diseases including lupus, psoriasis and chronic inflammatory diseases.