Cytomegalovirus infection induces the accumulation of short-lived, multifunctional CD4+CD45RA+CD27+ T cells: the potential involvement of interleukin-7 in this process |
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Authors: | Libri Valentina Azevedo Rita I Jackson Sarah E Di Mitri Diletta Lachmann Raskit Fuhrmann Stephan Vukmanovic-Stejic Milica Yong Kwee Battistini Luca Kern Florian Soares Maria V D Akbar Arne N |
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Institution: | Division of Infection and Immunity, University College London, London, UK. |
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Abstract: | The relative roles that ageing and lifelong cytomegalovirus (CMV) infection have in shaping naive and memory CD4+ T-cell repertoires in healthy older people is unclear. Using multiple linear regression analysis we found that age itself is a stronger predictor than CMV seropositivity for the decrease in CD45RA+ CD27+ CD4+ T cells over time. In contrast, the increase in CD45RA− CD27− and CD45RA+ CD27− CD4+ T cells is almost exclusively the result of CMV seropositivity, with age alone having no significant effect. Furthermore, the majority of the CD45RA− CD27− and CD45RA+ CD27− CD4+ T cells in CMV-seropositive donors are specific for this virus. CD45RA+ CD27− CD4+ T cells have significantly reduced CD28, interleukin-7 receptor α (IL-7Rα) and Bcl-2 expression, Akt (ser473) phosphorylation and reduced ability to survive after T-cell receptor activation compared with the other T-cell subsets in the same donors. Despite this, the CD45RA+ CD27− subset is as multifunctional as the CD45RA− CD27+ and CD45RA− CD27− CD4+ T-cell subsets, indicating that they are not an exhausted population. In addition, CD45RA+ CD27− CD4+ T cells have cytotoxic potential as they express high levels of granzyme B and perforin. CD4+ memory T cells re-expressing CD45RA can be generated from the CD45RA− CD27+ population by the addition of IL-7 and during this process these cells down-regulated expression of IL-7R and Bcl-2 and so resemble their counterparts in vivo. Finally we showed that the proportion of CD45RA+ CD27− CD4+ T cells of multiple specificities was significantly higher in the bone marrow than the blood of the same individuals, suggesting that this may be a site where these cells are generated. |
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Keywords: | ageing CD4 T cells CD45RA CMV IL‐7 |
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