IL21 and systemic lupus erythematosus: CREMα has been shown before to downregulate the TCR ζ chain and the IL-2 expression in SLE while enhancing secretion of IL-17 and IL-21 [12, 13, 16, 20, 31] and as shown here also dysregulates T cell responses in JIA as shown by our siRNA and in vivo studies.