IL21 and systemic lupus erythematosus: Although the exact role of central memory CD8+ T cells has not been sufficiently investigated in SLE (26), a few studies have reported that this T cell subset could be induced in the setting of autoimmunity due to stimulation by multiple cytokines, such as IL-2, IL-12, IL-15, IL-21, and type I IFNs, all of which are mediated via the JAK/STAT pathway (27).