IL21 and systemic lupus erythematosus: There is a super-functional Tfh-like cells subset in lupus-prone New Zealand Black x New Zealand White (NZBxW) mice, defined as IL-21+IFN-γhighPD-1lowCD40LhighCXCR5−Bcl-6− T cells, which express high levels of TNF-α and IL-2 and help B cells to produce IgG in an IL-21 and CD40L-dependent manner [121].