T-cells

Definition

T-cells, also known as T lymphocytes, are a type of white blood cell that play a crucial role in the adaptive immune response. They are responsible for recognizing and eliminating specific pathogens, infected cells, and cancerous cells, making them a key component in the body's defense against disease.

5 Must Know Facts For Your Next Test

1. T-cells are produced in the bone marrow and mature in the thymus gland, where they undergo a process called thymic selection to ensure they can recognize self from non-self.
2. T-cells express unique T-cell receptors (TCRs) on their surface that allow them to recognize specific antigens presented by major histocompatibility complex (MHC) molecules on the surface of other cells.
3. CD4+ T-cells coordinate the immune response by secreting cytokines that activate and regulate other immune cells, such as B-cells, macrophages, and CD8+ T-cells.
4. CD8+ T-cells directly kill infected or cancerous cells by releasing cytotoxic granules containing perforin and granzymes, which induce apoptosis in the target cell.
5. Regulatory T-cells (Tregs) are a specialized subset of T-cells that suppress the immune response to prevent autoimmunity and maintain immune homeostasis.

Review Questions

• Explain the role of T-cells in the adaptive immune response and how they contribute to the body's defense against disease.
  • T-cells are a crucial component of the adaptive immune system, responsible for recognizing and eliminating specific pathogens, infected cells, and cancerous cells. They express unique T-cell receptors (TCRs) that allow them to recognize antigens presented by major histocompatibility complex (MHC) molecules on the surface of other cells. CD4+ T-cells, also known as helper T-cells, coordinate the immune response by secreting cytokines that activate and regulate other immune cells, such as B-cells and CD8+ T-cells. CD8+ T-cells, or cytotoxic T-cells, directly kill infected or cancerous cells by releasing cytotoxic granules containing perforin and granzymes, which induce apoptosis in the target cell. This targeted response helps the body effectively fight against specific threats, making T-cells a vital part of the body's defense against disease.
• Describe the process of T-cell development and the importance of thymic selection in ensuring T-cells can recognize self from non-self.
  • T-cells are produced in the bone marrow and undergo a maturation process in the thymus gland, known as thymic selection. During this process, T-cell precursors develop into mature T-cells with unique T-cell receptors (TCRs) that can recognize specific antigens. The thymic selection process is crucial in ensuring that T-cells can recognize self from non-self, as it involves the elimination of T-cells that react too strongly to self-antigens (negative selection) and the positive selection of T-cells that can recognize foreign antigens presented by major histocompatibility complex (MHC) molecules. This ensures that the T-cell repertoire is capable of responding to a wide range of pathogens and foreign substances while avoiding autoimmune reactions against the body's own cells and tissues.
• Analyze the role of regulatory T-cells (Tregs) in maintaining immune homeostasis and preventing autoimmunity, and explain how their dysfunction can contribute to the development of autoimmune disorders like multiple sclerosis.
  • Regulatory T-cells (Tregs) are a specialized subset of T-cells that play a critical role in maintaining immune homeostasis and preventing autoimmunity. Tregs suppress the immune response by secreting inhibitory cytokines, such as IL-10 and TGF-β, and by directly interacting with and inhibiting the activation of other immune cells, such as effector T-cells and B-cells. This regulatory function is essential for preventing the immune system from attacking the body's own cells and tissues, which can lead to the development of autoimmune disorders. In the context of multiple sclerosis, an autoimmune disease characterized by the destruction of the myelin sheath surrounding nerve fibers in the central nervous system, dysfunction or depletion of Tregs is thought to contribute to the breakdown of self-tolerance and the subsequent autoimmune attack on the myelin. Understanding the role of Tregs in maintaining immune homeostasis and their potential dysregulation in autoimmune diseases like multiple sclerosis is crucial for developing targeted therapies and interventions.

Related terms

Adaptive Immune System: The adaptive immune system is a complex network of cells, tissues, and organs that work together to recognize and respond to specific foreign invaders, such as bacteria, viruses, and cancerous cells.

CD4+ T-cells: CD4+ T-cells, also known as helper T-cells, assist other immune cells in recognizing and responding to threats by releasing cytokines that coordinate the immune response.

CD8+ T-cells: CD8+ T-cells, also known as cytotoxic T-cells, directly kill infected or cancerous cells by releasing cytotoxic granules that induce apoptosis (programmed cell death).