Contribution of FoxP3 + Tfr cells to overall human blood CXCR5 + T cells

Summary The identification that T follicular helper (Tfh) cells is critical for the emergence of germinal centre responses prompted the study of CXCR5‐expressing CD4 + T cell subsets in autoimmunity. However, circulating CXCR5‐expressing T cells are heterogeneous by containing Forkhead box protein 3 (FoxP3) + T follicular regulatory (Tfr) cells in addition to bona fide Tfh cells. Such heterogeneity may hamper the analysis of the contribution of specific follicular T cell subsets for autoimmune pathogenesis. Therefore, separate assessment of Tfh and Tfr populations offer greater opportunities for stratification of autoimmune patients, such as Sjögren’s syndrome patients.