Human CD4+ Memory T Cells Are Preferential Targets for Bystander Activation and Apoptosis
Abstract There is much evidence that T cells may be activated via mechanisms that act independently of direct TCR ligation. Despite this, the question of whether such forms of bystander T cell activation occur during immune responses is hotly debated. To address some outstanding questions, we set up...
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| Главные авторы: | , , , , , |
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| Формат: | Artigo |
| Язык: | английский |
| Опубликовано: |
2009
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| Online-ссылка: | https://doi.org/10.4049/jimmunol.0802596 https://journals.aai.org/jimmunol/article-pdf/182/4/1962/1275648/zim00409001962.pdf |
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| Итог: | Abstract There is much evidence that T cells may be activated via mechanisms that act independently of direct TCR ligation. Despite this, the question of whether such forms of bystander T cell activation occur during immune responses is hotly debated. To address some outstanding questions, we set up an in vitro system within which to analyze bystander T cell activation in human T cells, in the absence of the possibility for TCR cross-reactivity. In addition, we have investigated the genetic, phenotypic, and functional characteristics of bystander-activated T cells. In this study, we show that bystander T cell activation is, indeed, observed during a specific immune response, and that it occurs preferentially among CD4+ memory T cells. Furthermore, bystander-activated T cells display a distinct gene expression profile. The mechanism for bystander T cell activation involves soluble factors, and the outcome is an elevated level of apoptosis. This may provide an explanation for the attrition of T cell memory pools of heterologous specificity during immune responses to pathogens such as viruses. |
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