IL21 and systemic lupus erythematosus: SLE patients’ CD4+ T cells under Tfh-polarizing conditions treated with the anti-IL-12 antibody inhibited differentiation of CD4+CXCR5+PD-1+ T cells and CD4+CXCR5+PD-1+Bcl-6+ T cells and downregulated IL-21 production (54).