BackgroundT cell-dependent B-cell responses decline with age, indicating declined cognate helper activity of aged CD4 + T cells for B cells. However, the mechanisms remain unclear. T follicular helper (Tfh) cells, a novel T helper subset, play an essential role in helping B cells differentiation into long-lived plasma cells in germinal center (GC) or short-lived plasma cells. In the present study, we proposed that there might existe changes of proportion, phenotype or cytokine production of blood Tfh cells in healthy elderly individuals compared with healthy young individuals.ResultsThe results showed that frequencies of aged blood CXCR5 + CD4 + Tfh cells increased compared with young subjects. Both aged and young blood CXCR5 + CD4 + Tfh cells constitutively expressed CD45RO, CCR7 and CD28, and few of these cells expressed CD69 or HLA-DR, which indicated that they were resting memory cells. There was no significant difference of IL-21 frequency production by aged blood CXCR5 + CD4 + Tfh determined by FACS compared with young individuals, however, aged PBMCs produced significantly higher levels of IL-21 evaluated by ELISA. Furthermore, there were no significant differences of percentages of IFN-γ, IL-4, IL-17 or IL-22 production by aged Tfh cells compared with their counterparts of young individuals respectively. However, frequencies of IL-17+ cells within aged CD4 + CXCR5-T cells were markedly lower than in the young individuals. Furthermore we observed different frequencies of IFN-γ, IL-17, IL-4 or IL-22 production by Tfh or by CD4 + CXCR5- cells in aged and young subjects respectively.ConclusionsOur data demonstrated that the frequencies of blood memory CXCR5 + CD4 + Tfh cells increased in the elderly population. There were similar frequencies of Th characterized cytokine production such as IL-21, IFN-γ, IL-4, IL-17 or IL-22 in aged and young Tfh cells. However, aged PBMCs produced a significantly higher amount of IL-21 compare to young subjects.

BackgroundChildren are prone to get infections, especially in the respiratory system and the gut mainly because their immune system is immature. T cells significantly contribute to the prevention of infections, and different helper T cell (Th) subsets play different anti-pathogen roles. Interleukin (IL)-22 producing by T-helper 22 cells (Th22) play an important role in host defense against Gram-negative bacterial organisms in gut and lung. T-helper 17 cells (Th17) protect against extracelluar bacteria and fungi especially at the epithelial surface. However, there is no report comparing IL-22 producing T cells and Th17 cells in healthy young children to adults.MethodsFlow cytometry (FCM) was used to observe whether Th22 subset existed in the peripheral blood of healthy young children. Meanwhile, we determined the frequencies of Th subsets including Th17, Th1 and Th2, cytotoxic T (Tc)1 subset, CD4+ and CD8+ memory T cells in the peripheral blood of both young children and adults.ResultsIn the present study, we demonstrated that Th22 subset existed in peripheral blood of children, with IL-22 mainly secreted by CD4 + CD45RO+ memory T cells. Moreover, we observed that IL-22 + CD4 + T cells and Th subsets including Th17, Th1, and Th2 frequencies of young children (1–6 years old) were significantly lower than adults. While the Th1 frequency from Group A (1–3 years old) was markedly lower than that from Group B (4–6 years old). No significant differences of Th17 or IL-22 + CD4 + T cells frequencies were observed between these two groups. In addition, Tc1 subset frequencies were also remarkably lower in young children than in adults. Furthermore, lower frequencies of CD45RO+ memory CD4+ and CD8+ T cells in young children than in adults, and significant correlation between CD45RO+ memory CD4 + T cells and IL-22 + CD4 + T cells, Th1, Th17 were observed.ConclusionsTh22 subset exists in the peripheral blood of young children. Compared with adults, there are lower frequencies of IL-22 + CD4 + T cells, as well as Th1, Th17, Th2 and Tc1 subsets in the peripheral blood of young children.

IL-22 is involved in psoriasis and exacerbates disease progression. Cyclosporine A (CsA) is an immunosuppressant drug that has been used in the treatment of psoriasis for more than 20 years. We determined IL-22 producing T cells and their phenotype, and demonstrated that IL-22 is mainly produced by CD4 + memory T cells not CD8 + T cells in peripheral blood from healthy adults. We compared Th17 and Th1 with the percentages of IL-22 producing CD4 + T cells, and demonstrated that Th1 is the majority Th subset in the blood, as the percentage of Th1 cells is significantly larger than the percentage of IL-22 producing CD4 + T cells or Th17 cells. We analyzed the correlation of IL-22, IL-17 and IFN-γ produced by CD4 + T cells from healthy adults, and confirmed that there is a subset of Th22 cells that does not produce IL-17 or IFN-γ. Furthermore, we observed that the percentage of IL-22 producing CD4 + T cells is elevated in psoriasis compared to healthy donors, and that the majority of these cells are memory CD4 + T cells. We also investigated the inhibitory effects of CsA on IL-22 production by CD4 + T cells from both healthy donors and patients with psoriasis. We observed that CsA inhibits the production of IL-22 by CD4 + T cells from healthy donors in a dose-dependent manner, and that it inhibits IL-22, IFN-γ and IL-17 production by CD4 + T cells in psoriasis. The obtained results provide critical information regarding the clinical efficacies of CsA in the treatment of psoriasis.

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