CXCR5 and graft versus host disease: We detected the proportions of CD4+CD25+FoxP3+ T cells (Treg) and CD4+CXCR5+FoxP3+ T cells (follicular regulatory T cells, Tfr), which were identified as important immunosuppressive T cells in GVHD pathogenesis, in splenocytes on day 14 post-transplantation.