Human CD4+ memory T cells are preferential targets for bystander activation and apoptosis.

Journal article

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.

Authors: Bangs, S; Baban, D; Cattan, H; Li, C; Mcmichael, A

• Publication status: Published
• Journal: Journal of Immunology
• Volume: 182
• Issue: 4
• Pages: 1962-1971
• Publication date: 2009-02-01
• DOI: 10.4049/jimmunol.0802596
• EISSN: 1550-6606
• ISSN: 0022-1767
• Language: English
• Keywords: Lymphocyte Activation; Apoptosis; Immunologic Memory; Flow Cytometry; Oligonucleotide Array Sequence Analysis; Humans; Gene Expression Profiling; CD4-Positive T-Lymphocytes; Reverse Transcriptase Polymerase Chain Reaction; Bystander Effect