CXCR5 and rheumatoid arthritis: We measured the frequency of the Th cells (CD4+CD127+CD25−/lo), Treg cells (CD4+CD127−/loCD25+), and non-Th/Treg cells (CD4+CD127-CD25−), and within these subsets, we also evaluated the frequency of circulating follicular helper T (cTfh) cells (CD4+CXCR5+CD127+CD25−/lo), circulating follicular regulatory T (cTfr) cells (CD4+CXCR5+CD127−/loCD25+) and non-cTfh/cTfr cells (CD4+CXCR5+CD127−CD25−), respectively, among the HCs and RA patients (Figure 1a,b and Figure S1a,b).