Review of IL-21 - made by follicular helper T & Th17 cells; promotes B cell maturation/function, mediated thru activation of the JAK/STAT, MAPK, PI3K pathways. IL-21 is increased in autoimmune patients - may be Rx target in RA, SLE, RA, T1D, PsA https://t.co/ld1Q3fHw9N