Relationship between Tfh cells and the other Th cell subsets in human peripheral blood and tonsils

This paper aimed to compare the phenotypes of Tfh cells as well as evaluate the relationship of Tfh cells with Th1,Th17 and Th22 cell subsets in human peripheral blood and tonsils.We isolated PBMCs and tonsillar mononuclear cells,then detected the production of cytokines by ELISA and FACS after stimulation with anti-CD3 plus anti-CD28 or PMA plus ionomycin.Finally,the relationship of Tfh cells with Th1,Th17 and Th22 cell subsets was identified.Different from what observed in PBMCS,higher expression of CXCR5 and CD45RO and lower expression of CCR7 and CD62L were demonstrated in tonsillar CD4+ T cells.Tonsillar CD4+ T cells produced higher levels of IL-21 and IL-17 but lower level of IFN-γ compared with CD4+ T cells in PBMCs.While the level of IL-22 was similar in PBMC and tonsillar CD4+ T cells.A few of IL-21+ IL-17+,IL-21+ IL-22+ and IL-21+ IFN-γ+ cells were existed both in PBMC and tonsillar CD4+ T cells.Furthermore,the frequencies of IL-21 single positive cells were higher in tonsillar CD4+ T cells than in CD4+ T cells from PBMCs.Besides co-expression with IL-21,some proportion of CD4+ CXCR5+ cells in PBMCs and tonsils are IL-17-positve,IL-22-positive or IFN-γ-positive.We concluded that there are higher amount of Tfh cells in tonsils than in PBMCs,and the majority of Tfh cells belong to a distinct subset from Th1,Th17,or Th22 cells.