T cells

Definition

T cells are a type of white blood cell that play a crucial role in the adaptive immune system by recognizing and responding to specific pathogens. They are essential for cell-mediated immunity, distinguishing between self and non-self cells, and orchestrating the immune response through various subtypes. T cells can directly kill infected cells, help other immune cells, and remember past infections for quicker responses in the future.

5 Must Know Facts For Your Next Test

1. T cells originate from stem cells in the bone marrow but mature in the thymus, where they develop their unique receptors.
2. There are two main types of T cells: CD4+ (helper) T cells and CD8+ (cytotoxic) T cells, each with distinct functions in the immune response.
3. Activation of T cells requires antigen presentation by major histocompatibility complex (MHC) molecules on the surface of antigen-presenting cells.
4. Once activated, T cells undergo clonal expansion, producing many identical cells that are specific to the invading pathogen.
5. T cell responses can lead to the development of immunological memory, which is vital for long-term immunity against previously encountered pathogens.

Review Questions

• Explain how T cells contribute to the adaptive immune response and differentiate between their various subtypes.
  • T cells are key players in the adaptive immune response by recognizing specific antigens presented by other immune cells. There are several subtypes, including helper T cells that enhance the immune response by releasing cytokines and cytotoxic T cells that directly kill infected or cancerous cells. This differentiation allows for a coordinated immune attack tailored to specific pathogens, making T cells crucial for effective immunity.
• Discuss the importance of MHC molecules in the activation of T cells during an immune response.
  • MHC molecules are essential for presenting antigens to T cells, enabling their activation. Helper T cells recognize antigens presented by MHC class II molecules on antigen-presenting cells, while cytotoxic T cells engage with MHC class I molecules found on all nucleated cells. This interaction is critical for T cell recognition of infected or abnormal cells, ultimately triggering an appropriate immune response.
• Evaluate the role of memory T cells in long-term immunity and how this impacts vaccination strategies.
  • Memory T cells play a vital role in long-term immunity by retaining information about previously encountered pathogens. When re-exposed to the same antigen, these memory T cells can quickly proliferate and mount a robust immune response. This principle is fundamental to vaccination strategies, as vaccines aim to create memory T cell populations without causing disease, ensuring rapid protection against future infections.

Related terms

Helper T cells: A subtype of T cells that assist other immune cells by releasing cytokines and enhancing the immune response.

Cytotoxic T cells: A type of T cell that directly attacks and destroys infected or cancerous cells.

Memory T cells: Long-lived T cells that remember past infections, enabling a faster and more effective response upon re-exposure to the same pathogen.