IL21 and systemic lupus erythematosus: Moreover, the Vδ2 T cell-mediated expression of CD40L and production of IL-21 were downregulated in SLE patients after treatment (15.06 ± 6.04% vs. 51.06 ± 13.04% and 27.69 ± 5.35% vs. 51.69 ± 13.04%, respectively, p < 0.05) (Fig. 7C–D).