Regulatory T-Cells

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Immunology

Summary

Unlike helper or killer T-cells, regulatory T-cells control the immune system by suppressing or controlling the immune response, thereby eliminating self-reactive T-cells that have escaped from the thymus, a function referred to as peripheral tolerance. They play a significant role in preventing autoimmune diseases and inhibiting the activation and proliferation of antigen-presenting cells like B cells, dendritic cells, and macrophages. Regulatory T-cells express CD4 and CD25, which is a component of the IL-2 receptor. They're stimulated by IL-2 and inhibited by IL-6. Regulatory T-cells release anti-inflammatory cytokines such as TGF-beta, IL-10, and IL-35. T In addition, the transcription factor FOXP3 oversees the development and function of regulatory T-cells. Mutations in FOXP3 are associated with a rare autoimmune disorder called IPEX syndrome, which can lead to issues such as immune dysregulation, polyendocrinopathy, enteropathy, and X-linked syndrome.

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FAQs

What is the role of Cytotoxic T-cells in our immune system?

Cytotoxic T-cells, also known as CD8+ T-cells, play a crucial role in our immune system. They are part of the adaptive immune system, meaning they help our body combat pathogens in a highly specific manner. Cytotoxic T-cells recognize virus-infected cells, tumor cells, and cells harboring intracellular bacteria, and cause their elimination through programmed cell death or apoptosis.

How do Cytotoxic T-cells recognize virus-infected cells or tumor cells?

Cytotoxic T-cells recognize infected or cancerous cells through MHC class one molecules present on the surface of all nucleated cells. These cells display processed antigens, i.e., parts of the proteins from within the cell, to the outside world. If these antigens are foreign, like those from viruses or mutated as in tumor cells, the cytotoxic T-cell recognizes this and triggers cell death.

What are Type 4 hypersensitivity reactions and how are they related to Cytotoxic T-cells?

Type 4 hypersensitivity reactions, also known as delayed-type hypersensitivity reactions, are immune responses that take place several hours to days after exposure to an antigen. Cytotoxic T-cells are a key player in these reactions. They induce cell death when they recognize an antigen presented by MHC class one molecules on antigen-presenting cells, causing tissue damage in the process.

What role do Cytotoxic T-cells play in autoimmune diseases?

Autoimmune diseases occur when the immune system mistakenly attacks normal body cells. In some cases, this is due to cytotoxic T-cells incorrectly recognizing self-antigens as foreign. Instead of targeting virus-infected cells or tumor cells, these cytotoxic T-cells target healthy cells, leading to tissue damage and the manifestation of autoimmune diseases.

How are Antigen-Presenting Cells (APCs) involved in the activation of Cytotoxic T-cells?

Antigen-presenting cells (APCs) play a key role in activating cytotoxic T-cells. APCs, such as dendritic cells, ingest pathogens and present their antigens on their surface using MHC class one molecules. When a cytotoxic T-cell recognizes the antigen being presented, it becomes activated and goes on to target and destroy any cells in the body that are displaying the same antigen.

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