Figure 1.

Heterogeneity of human blood CXCR5‐expressing CD4 T cells. (a) Circulating CD4⁺ T cells that express CXCR5 contain a proportion of cells expressing forhead box protein 3 (FoxP3) (representative plots from healthy donors). (b) When FoxP3⁺ and FoxP3^– CD4⁺ T cells are analysed separately (i.e. gated as regulatory T cells (T_reg) and conventional T (T_conv) cells, respectively), it becomes apparent that among the two populations there is a proportion of cells expressing CXCR5. Follicular subsets defined by expression of CXCR3 and CCR6 are different among T follicular regulatory (Tfr) cells (defined as FoxP3⁺CXCR5⁺CD4 T cells) and T follicular helper (Tfh) cells. Representative plots and pooled data from healthy donors (n = 42). (c) Sjögren’s syndrome (SS) patients display an increased frequency of circulating Tfr cells, with no significant changes when Tfh cells or the overall CXCR5‐expressing CD4⁺ T cells are considered as a whole (n = 16).