IL21 and systemic lupus erythematosus: Furthermore, TLR7 and B-cell receptor (BCR) agonists cooperate with IFNγ, IL-2, IL-21 and B-lymphocyte stimulator (BlyS) to stimulate naive human B cells in SLE, and an in vitro study reported that the produced IgD−CD27−CD11c+T-BethiCD21−CXCR5−IRF4intFcRL5+ B cells resemble DN2 B cells (52).