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Divide, Conquer, and Sense: CD8+CD28- T Cells in Perspective
Fernando A Arosa1, André J Esgalhado2, Carolina A Padrão2
1Health Sciences Research Centre (CICS-UBI), Universidade da Beira Interior, Covilhã, Portugal; Faculty of Health Sciences (FCS-UBI), Universidade da Beira Interior, Covilhã, Portugal.
Insights
Highly differentiated CD8+ T cells (CD8+CD28-) possess innate receptors and sense TCR-independent signals. These cells are crucial for tissue homeostasis, not dysfunctional, and are found in healthy elderly and inflammatory conditions.
Area of Science:
- Immunology
- Cellular Biology
Background:
- CD8+ T cells are crucial for adaptive immunity.
- Effector memory CD8+ T cells (CD8+CD28-) exhibit unique characteristics.
- These cells express innate receptors and have reduced T cell receptor (TCR) signaling.
Purpose of the Study:
- To understand the generation and function of CD8+CD28- T cells.
- To investigate the role of these cells in tissue homeostasis.
- To explore their presence in elderly individuals and inflammatory conditions.
Main Methods:
- Analysis of CD8+ T cell populations.
- Characterization of receptor expression (TCR, CD28, innate receptors).
- Assessment of T cell function in various conditions.
Main Results:
- CD8+CD28- T cells display a diverse array of innate receptors.
- These cells have a weakened capacity for peptide-MHC class I scrutiny via TCR.
- They are prevalent in healthy centenarians and chronic inflammatory states.
Conclusions:
- CD8+CD28- T cells are not dysfunctional but experienced cells.
- Their TCR-independent signaling allows them to fine-tune tissue homeostasis.
- Understanding these cells is key in contemporary human immunology.
Abstract:
Understanding the rationale for the generation of a pool of highly differentiated effector memory CD8+ T cells displaying a weakened capacity to scrutinize for peptides complexed with major histocompatibility class I molecules via their T cell receptor, lacking the "signal 2" CD28 receptor, and yet expressing a highly diverse array of innate receptors, from natural killer receptors, interleukin receptors, and damage-associated molecular pattern receptors, among others, is one of the most challenging issues in contemporary human immunology. The prevalence of these differentiated CD8+ T cells, also known as CD8+CD28-, CD8+KIR+, NK-like CD8+ T cells, or innate CD8+ T cells, in non-lymphoid organs and tissues, in peripheral blood of healthy elderly, namely centenarians, but also in stressful and chronic inflammatory conditions suggests that they are not merely end-of-the-line dysfunctional cells. These experienced CD8+ T cells are highly diverse and capable of sensing a variety of TCR-independent signals, which enables them to respond and fine-tune tissue homeostasis.
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