T-cell

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 cell-mediated immunity, recognizing and destroying infected or cancerous cells, and coordinating the overall immune response.

5 Must Know Facts For Your Next Test

1. T-cells originate from hematopoietic stem cells in the bone marrow and undergo maturation in the thymus gland, where they develop their unique T-cell receptor (TCR).
2. There are several subtypes of T-cells, including helper T-cells (CD4+), cytotoxic T-cells (CD8+), regulatory T-cells, and memory T-cells, each with specialized functions.
3. Helper T-cells coordinate the overall immune response by activating and directing other immune cells, such as B-cells and cytotoxic T-cells.
4. Cytotoxic T-cells directly recognize and destroy infected or cancerous cells by inducing apoptosis (programmed cell death).
5. Regulatory T-cells play a crucial role in maintaining immune homeostasis and preventing autoimmune diseases by suppressing excessive immune responses.

Review Questions

• Explain the role of T-cells in the adaptive immune response.
  • T-cells are a critical component of the adaptive immune system, responsible for cell-mediated immunity. They recognize and respond to specific antigens presented by the major histocompatibility complex (MHC) on the surface of infected or cancerous cells. This triggers the activation and proliferation of T-cells, which then carry out various effector functions, such as direct cytotoxicity, cytokine production, and the coordination of the overall immune response. By targeting and eliminating infected or transformed cells, T-cells play a vital role in protecting the body against pathogens and malignancies.
• Describe the different subtypes of T-cells and their specialized functions.
  • There are several distinct subtypes of T-cells, each with unique roles in the immune response. Helper T-cells (CD4+) coordinate the overall immune response by activating and directing other immune cells, such as B-cells and cytotoxic T-cells. Cytotoxic T-cells (CD8+) directly recognize and destroy infected or cancerous cells through the induction of apoptosis. Regulatory T-cells suppress excessive immune responses, maintaining immune homeostasis and preventing autoimmune diseases. Memory T-cells provide long-term protection by rapidly responding to previously encountered pathogens. The specialized functions of these T-cell subtypes allow for a comprehensive and balanced immune response to a wide range of threats.
• Analyze the importance of the thymus gland in the development and maturation of T-cells.
  • The thymus gland plays a crucial role in the development and maturation of T-cells. Hematopoietic stem cells from the bone marrow migrate to the thymus, where they undergo a complex process of selection and differentiation. Within the thymus, T-cell precursors rearrange their T-cell receptor (TCR) genes, express MHC-restricted TCRs, and undergo positive and negative selection to ensure the production of functional and self-tolerant T-cells. This maturation process in the thymus is essential for the generation of a diverse and effective T-cell repertoire, which is vital for the adaptive immune response. Disruptions in thymic function can lead to immunodeficiencies or autoimmune disorders, underscoring the importance of the thymus in T-cell development.

Related terms

Lymphocyte: A type of white blood cell that is essential for the adaptive immune response, including T-cells and B-cells.

Antigen: A substance that is recognized by the immune system as foreign and can trigger an immune response, such as the activation of T-cells.

Major Histocompatibility Complex (MHC): A group of genes that encode proteins involved in the presentation of antigens to T-cells, allowing them to recognize and respond to foreign substances.