IL21 and systemic lupus erythematosus: To investigate whether the IFN type I signature is associated with an increase in Th17 cytokines expressed by memory CCR6+ T cells, we measured the percentages of IL-17A, IL-17F, IL-22 and IL-21 producing CCR6+ T memory cells in SLE patients positive for the IFN type I signature (IFN+) and patients negative for the signature (IFN-) and HC.