In SLE (but not in psoriasis), we observed a significant up-regulation of CXCR5 (cumulative data in Fig. 5A; gating strategy in Fig. S6A–C) and IL-21 production (Fig. 5B) by LL37/cit-LL37 proliferating T-cells. This evidence concerns the gene IL21 and systemic lupus erythematosus.