T cells

Definition

T cells are a type of white blood cell that play a central role in the adaptive immune response, specifically targeting and eliminating infected cells and coordinating the immune response. They originate from bone marrow but mature in the thymus, where they gain the ability to recognize specific antigens presented by infected or abnormal cells. T cells are crucial in defending against viral infections, contributing to the body’s ability to remember past infections for quicker responses upon re-exposure.

5 Must Know Facts For Your Next Test

1. T cells can be classified into various subtypes, including cytotoxic T cells and helper T cells, each with distinct functions in the immune response.
2. Upon encountering their specific antigen presented by major histocompatibility complex (MHC) molecules on infected cells, T cells become activated and proliferate.
3. The activation of T cells leads to clonal expansion, where multiple identical copies of a T cell are produced to effectively target the infection.
4. T cell receptor (TCR) diversity is generated through a process called V(D)J recombination, allowing T cells to recognize a vast array of antigens.
5. Regulatory T cells help maintain immune tolerance by preventing excessive immune responses that could lead to tissue damage or autoimmune diseases.

Review Questions

• How do T cells contribute to the elimination of viral infections in the body?
  • T cells play a crucial role in eliminating viral infections by directly targeting and killing infected host cells. Cytotoxic T cells recognize viral antigens presented on the surface of these infected cells and initiate apoptosis, effectively removing the source of the virus. Additionally, helper T cells enhance the overall immune response by activating B cells and other immune components, ensuring a coordinated attack against the virus.
• Discuss the differences between cytotoxic T cells and helper T cells in terms of their roles and mechanisms of action.
  • Cytotoxic T cells and helper T cells serve distinct yet complementary roles in the immune system. Cytotoxic T cells are primarily responsible for directly killing infected or cancerous cells through recognition of specific antigens presented by MHC class I molecules. In contrast, helper T cells facilitate immune responses by releasing cytokines that activate B cells, promote antibody production, and enhance the activity of other immune cells. This coordination is vital for a robust and effective adaptive immune response.
• Evaluate the importance of memory T cells in long-term immunity and their role in vaccination strategies.
  • Memory T cells are essential for long-term immunity because they provide rapid and effective responses upon re-exposure to previously encountered pathogens. After an initial infection or vaccination, these long-lived cells persist in the body and can quickly recognize and respond to the same antigen, significantly reducing disease severity. This principle is leveraged in vaccination strategies, which aim to create a strong memory T cell response to protect individuals from future infections, illustrating how understanding T cell biology is key to improving vaccine efficacy.

Related terms

Cytotoxic T cells: A subtype of T cells that directly kill infected or cancerous cells by recognizing specific antigens presented on their surfaces.

Helper T cells: A subtype of T cells that assist other immune cells by releasing cytokines and enhancing their responses, including B cell activation.

Memory T cells: Long-lived T cells that remain in the body after an infection has been cleared, providing rapid and robust responses to subsequent infections by the same pathogen.