CXCR5 and systemic lupus erythematosus: Besides, Tfr subsets:Tfh subset ratios in SLE were dramatically decreased, including CXCR5+PD-1low Treg/Tfh (P=0.043), CXCR5+PD-1high Treg/Tfh (P<0.001), CXCR5+PD-1low Treg/Tfh17 (P=0.052), and CXCR5+PD-1high Treg/Tfh17 (P<0.001).