PDCD1 and systemic lupus erythematosus: Interestingly, the proportion of PD-1+cells incTfh1, cTfh2 and cTfh17 cells was remarkably increased in active and inactive SLE patients compared to HCs, and only ICOS+PD-1+cTfh1 cell (but not ICOS+PD-1+cTfh2 and ICOS+PD-1+cTfh17 cell) frequencies were significantly increased in active SLE patients and correlated with plasmablasts number, meanwhile, we also found cTfh1which expressing IFN-γ was increased in the peripheral blood of MRL/lpr mice.