Circulating Tfh cells are decreased after anti-CD20 rituximab treatment. (A) ICOS^hi PD-1^hi expression on live circulating Tfh CD45⁺CD3⁺CD4⁺CD45RO⁺CXCR5⁺ cells. (B) Percentage of circulating Tfh cells among total live CD4⁺ cells in healthy donors (HD) and in allo-SCT recipients with no cGVHD, at diagnosis of cGVHD, and 12 months after the diagnosis of cGVHD and rituximab treatment (mean, standard error of the mean). (C) Absolute values of circulating Tfh cells. (D) Percentage of ICOS^hi PD-1^hi cells among total live circulating Tfh cells (mean, standard error of the mean). (E) Whisker plots represent plasma CXCL13 concentrations in healthy donors and in each patient group after allo-SCT. HD, healthy donors.