Further studies in lupus-prone MRL/Mp-lpr/lpr (MRL/lpr) and B6.Sle1.Yaa mice revealed a beneficial effect after IL-21 neutralization in autoantibody production and also reduced renal-infiltrating Tfh and Th1 cells, improved renal histology, and reduced GC B cells and CD138hi plasmablasts. Here, IL21 is linked to systemic lupus erythematosus.