CD 8+ Cytotoxic T-Cells (CTC)
Cytotoxic T-Cells (CTC)
Cytotoxic T-cells (CTC), also known as cytotoxic T lymphocytes (CTLs) or CD8+ T-cells, are a vital component of the adaptive immune system. They play a crucial role in identifying and eliminating infected or cancerous cells. Their ability to directly kill target cells makes them essential for controlling viral infections and tumor surveillance.
Development and Activation
- Origin: Cytotoxic T-cells originate from hematopoietic stem cells in the bone marrow and mature in the thymus, where they undergo selection processes to ensure self-tolerance and functionality.
- Activation:
- Antigen Presentation: CTLs are activated when they encounter specific antigens presented by antigen-presenting cells (APCs) on MHC Class I molecules. This interaction is essential for their activation.
- Co-Stimulation: In addition to recognizing the antigen, CTLs require co-stimulatory signals provided by APCs (e.g., CD80/CD86 binding to CD28 on T-cells) for full activation.
- Cytokine Environment: The presence of cytokines, particularly interleukin-2 (IL-2), promotes CTL proliferation and differentiation.
Mechanisms of Action
Once activated, cytotoxic T-cells employ several mechanisms to eliminate target cells:
Perforin and Granzymes:
- CTLs release perforin, which forms pores in the target cell membrane, allowing granzymes (serine proteases) to enter the cell. Granzymes induce apoptosis (programmed cell death) in the target cell.
Fas Ligand Pathway:
- CTLs express Fas ligand (FasL), which binds to the Fas receptor on target cells, triggering apoptosis through a different signaling pathway.
Cytokine Production:
- CTLs secrete cytokines such as tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ), which enhance the immune response by activating other immune cells and promoting inflammation.
Role in Immune Responses
- Viral Infections: Cytotoxic T-cells are critical for controlling viral infections by killing virus-infected cells and preventing the spread of the virus.
- Tumor Immunity: CTLs play a significant role in recognizing and destroying tumor cells, contributing to cancer immunotherapy strategies such as CAR-T therapy.
- Transplant Rejection: CTLs can also mediate graft rejection by targeting foreign antigens presented by transplanted tissues.
Conclusion
Cytotoxic T-cells are essential for effective immune responses against infections and tumors. Their ability to specifically recognize and eliminate compromised cells underscores their importance in maintaining immune surveillance and homeostasis. Understanding the mechanisms of CTL activation and function is crucial for developing immunotherapies aimed at enhancing anti-tumor immunity and controlling infectious diseases. At DrStemCellsThailand‘s Anti-Aging and Regenerative Medicine Center of Thailand, we utilize insights from immunology to optimize therapeutic strategies for our patients.
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References
- Cytotoxic T-Cell Activation and Function
This article discusses the mechanisms involved in cytotoxic T-cell activation and their role in immune responses.
DOI: 10.1016/j.jdiacomp.2020.107646 - Mechanisms of Cytotoxicity in T-Lymphocytes
This review highlights the various mechanisms through which cytotoxic T-cells eliminate infected or malignant cells.
DOI: 10.1016/j.stemcr.2021.05.005 - The Role of Cytotoxic T-Cells in Cancer Immunotherapy
This study evaluates the contributions of cytotoxic T-cells to cancer immunotherapy strategies, including CAR-T therapy.
DOI: 10.1016/j.biopsych.2018.03.006
