Although IL-21 can exert certain suppressive functions on immunity, it is mainly known for its broad capacity to stimulate the proliferation and activity of pro-inflammatory pathways involved in the immunopathogenesis of MS and other autoimmune diseases such as rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE) [8, 9]. Here, IL21 is linked to systemic lupus erythematosus.