IL21 and systemic lupus erythematosus: In an attempt to exemplify a role of T-bet+ B cells in human autoimmunity, Wang et al. described an unusual B cell subset (termed CD11chiT-bet+ B cells) in patients with SLE, that displays many of the ABC key characteristics.31 In more detail, these cells express CD11c surface marker, and the transcription factor T-bet, expand in patients with SLE and also differentiate into autoreactive ASC in an IL-21 dependent manner.31 Moreover, similar to ABCs, these cells are BAFFR+ and TACI+.3,31