Recent

  • Show all results for ""

🎧 New: AI-Generated Podcasts Turn your study notes into engaging audio conversations. Learn more

IMM: BLOCK 2: LECTURE 8: T-CELL ACTIVATION AND EFFECTOR FUNCTION
45 Questions
0 Views

IMM: BLOCK 2: LECTURE 8: T-CELL ACTIVATION AND EFFECTOR FUNCTION

Created by
@ImmenseBixbite1566

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the function of regulatory T cells (Tregs) in the immune response?

  • Suppress the immune response to prevent autoimmunity (correct)
  • Help in the production of antibodies by B cells
  • Promote the activation of all T cells
  • Enhance cytokine production in effector T cells

    • Which mechanism is primarily utilized by cytotoxic CD8 T cells to eliminate infected cells?

  • Secreting cytokines that promote inflammation
  • Producing antibodies against pathogens
  • Initiating T-cell priming in lymph nodes
  • Directly lysing target cells using perforin and granzymes (correct)

    • What role do cytokines play in T cell function?

  • They have no significant role in regulating T cell activities
  • They serve as primary signals to activate T cells
  • They help in the differentiation and activation of T cells (correct)
  • They are only produced by B cells

    • What is the significance of CD40L in T cell interactions?

    <p>It enhances B cell responses through interactions with CD40</p> Signup and view all the answers

    What happens to naive T cells when they recognize an antigen without co-stimulation?

    <p>They enter a state of anergy and become non-responsive</p> Signup and view all the answers

    What is the consequence of T cells being in an anergic state?

    <p>They are unable to respond to their specific antigen.</p> Signup and view all the answers

    Which cytokine is primarily responsible for the proliferation and differentiation of activated naive T cells?

    <p>Interleukin-2 (IL-2)</p> Signup and view all the answers

    What determines the differentiation pathway a naive T cell takes during activation?

    <p>The cytokine environment.</p> Signup and view all the answers

    What is the role of TH1 CD4 cells in the immune response?

    <p>To induce macrophage activation.</p> Signup and view all the answers

    Which form of receptor is expressed by naive T cells for interleukin-2?

    <p>A unique form not expressed by activated T cells.</p> Signup and view all the answers

    What is the first step in the activation of a naive B cell by a TFH cell?

    <p>The naive B cell binds antigen with its BCR.</p> Signup and view all the answers

    What interaction leads to the expression of CD40L on TFH cells during B cell activation?

    <p>Cognate pair formation with the B cell.</p> Signup and view all the answers

    Which type of CD4 T cell is associated with an anti-inflammatory response?

    <p>TH2</p> Signup and view all the answers

    What is the primary function of regulatory CD4 T cells (Treg)?

    <p>To limit the activities of effector CD4 and CD8 T cells</p> Signup and view all the answers

    How do CD8 T cells induce apoptosis in their target cells?

    <p>Through the release of perforin and granzymes</p> Signup and view all the answers

    What is the role of IL-2 in T cell activation?

    <p>It aids in activating naive CD8 T cells when secreted by CD4 T cells</p> Signup and view all the answers

    What two molecules are involved in T cell interactions with antigen-presenting cells (APCs)?

    <p>LFA-1 and CD40L</p> Signup and view all the answers

    Which statement about naive T cell activation is true?

    <p>Naive CD8 T cells can be activated directly by virus-infected cells</p> Signup and view all the answers

    Why do memory T cells decrease L-selectin expression?

    <p>To allow them to home to sites of inflammation instead of lymph nodes</p> Signup and view all the answers

    What is a consequence of interaction between CD40L on T cells and its receptor?

    <p>It enhances the activation of B cells</p> Signup and view all the answers

    What is the function of VLA-4 integrin expressed by effector T cells?

    <p>To allow adhesion to endothelial cells in inflamed tissue</p> Signup and view all the answers

    Which of the following statements about effector CD8 T cells is NOT true?

    <p>They require co-stimulation for activation.</p> Signup and view all the answers

    What important role does IL-17 play in T cell functions?

    <p>It is crucial for the development of T follicular helper cells.</p> Signup and view all the answers

    What is the purpose of the immunological synapse?

    <p>To facilitate T cell activation and signal transduction</p> Signup and view all the answers

    Which of the following signals triggers T cell anergy?

    <p>Recognition of antigen in the absence of co-stimulation</p> Signup and view all the answers

    What role do ITAMs play in the context of T cell activation?

    <p>They facilitate the signaling process during T cell activation</p> Signup and view all the answers

    Which sub-type of CD4+ T cells is primarily responsible for activating macrophages?

    <p>TH1 cells</p> Signup and view all the answers

    Which statement accurately describes a memory T cell?

    <p>A T cell that has previously encountered an antigen and can respond rapidly upon re-exposure</p> Signup and view all the answers

    What indicates that naive T cells cannot respond to their specific antigen?

    <p>They are in an anergic state.</p> Signup and view all the answers

    Which chains are part of the interleukin-2 (IL-2) receptor unique to T cells?

    <p>Alpha, beta, and gamma chains.</p> Signup and view all the answers

    Which factor primarily determines the type of effector CD4 T cell produced from naive CD4 T cells?

    <p>The cytokine environment.</p> Signup and view all the answers

    What is the primary function of TH1 CD4 effector cells?

    <p>Inducing macrophage activation.</p> Signup and view all the answers

    During the activation of a naive B cell, which step follows the binding of the antigen with the B cell receptor (BCR)?

    <p>The antigen is internalized and presented via MHC II.</p> Signup and view all the answers

    How do naive B cells interact with TFH cells during their activation?

    <p>By recognizing the same epitope of the antigen.</p> Signup and view all the answers

    Which aspect of TFH cell activation is critical for the naive B cell function?

    <p>Cognate interaction leading to CD40L expression.</p> Signup and view all the answers

    Which type of helper T cell is characterized as having an anti-inflammatory phenotype?

    <p>TH2 CD4 cells.</p> Signup and view all the answers

    What is required for the activation of naive CD8 T cells when direct activation by a dendritic cell is insufficient?

    <p>Co-stimulation from CD4 T cells</p> Signup and view all the answers

    Which molecule is primarily responsible for effector T cells homing to inflamed tissues?

    <p>VCAM-1</p> Signup and view all the answers

    Which T cell type primarily employs the secretion of IL-2 to facilitate the activation of naive CD8 T cells?

    <p>Effector CD4 T cells</p> Signup and view all the answers

    What characteristic change occurs in memory T cells regarding L-selectin expression?

    <p>Decreased expression to favor different tissue homing</p> Signup and view all the answers

    What type of cytokines do effector T cells primarily release to mediate their functions?

    <p>Cytokines and cytotoxins</p> Signup and view all the answers

    What is the mechanism by which autoreactive Treg cells prevent the proliferation of autoreactive helper CD4 T cells?

    <p>By interacting with the same APC and using cytokine signals</p> Signup and view all the answers

    What role does CD58 play in T cell activation?

    <p>It serves as a backup for co-stimulation in CD8 T cells</p> Signup and view all the answers

    What happens to CD8 T cells that lack CD28 co-stimulation?

    <p>They require CD58 for further activation</p> Signup and view all the answers

    Which cytokine is key in the differentiation of T follicular helper cells that aid in B cell function?

    <p>IL-21</p> Signup and view all the answers

    Study Notes

    T Cell Anergy

    • T cells become anergic when they are unable to respond to their specific antigen.
    • Anergy is a state of non-responsiveness.

    Naive T Cell Activation

    • Activation of naive T cells by antigen is driven by the cytokine interleukin-2 (IL-2).
    • Naive and activated T cells express different forms of the IL-2 receptor.
    • The IL-2 receptor is composed of alpha, beta, and gamma chains, separate from the TCR.

    Naive CD4 T Cell Differentiation

    • Activation of naive CD4 T cells creates five types of effector CD4 T cells.
    • The cytokine environment determines the differentiation pathway a naive T cell takes.

    Effector CD4 T Cell Subtypes

    • TH1 Cells - induce macrophage activation making macrophages microbicidal.
    • TH2 Cells - have an anti-inflammatory phenotype.
    • TFH (Follicular Helper) Cells - recognize different epitopes of the same antigen as naive B cells.
    • Treg Cells - limit the activities of effector CD4 and CD8 T cells.
    • TH17 Cells - promote inflammation and are thought to play a role in autoimmune diseases.

    Naive CD8 T Cell Activation

    • Naive CD8 T cells require stronger activation than naive CD4 T cells.
    • Naive CD8 T cells can be activated directly by a virus-infected dendritic cell.
    • Naive CD8 T cells can be activated indirectly by a dendritic cell with insufficient co-stimulation, helped by CD4 effector T cells.
    • IL-2 secreted by CD4 T cells can act directly on naive CD8 T cells interacting with the same dendritic cell.

    CD8 T Cell Co-stimulation

    • Some CD8+ T cells lack CD28.
    • CD58 acts as a backup for co-stimulation by binding to CD2.

    Effector T Cell Functions

    • Effector CD8 T cells and effector CD4 TH1, TH2, and TH17 cells work at sites of infection.
    • The integrin VLA-4 enables effector T cells to home to inflamed tissue.
    • Effector T cell functions are mediated by cytokines and cytotoxins.

    Cytotoxic CD8 T Cell Activity

    • Cytotoxic CD8 T cells are selective and serial killers of infected target cells.
    • Cytotoxic CD8 T cells kill target cells by inducing apoptosis.

    Memory T Cells

    • Some CD4+ T cells enter a memory state.
    • Memory T cells express CD28, increase some adhesion molecules, but decrease surface expression of L-selectin.
    • Memory CD8+ T cells can also form.

    Immunological Synapse

    • The immunological synapse is formed by T-cell and antigen-presenting cell (APC) interactions.

    T-Cell Signal Transduction

    • T-cell signal transduction is the process by which T cells receive and respond to signals from the environment.
    • This process involves various signaling molecules, including the T-cell receptor (TCR) complex, co-receptors, and co-stimulatory receptors.

    Importance of IL-2

    • IL-2 plays a crucial role in T cell activation, proliferation, and differentiation.
    • IL-2 is a growth factor that promotes the expansion of activated T cells, allowing them to mount a robust immune response.

    Co-Stimulatory Molecules

    • Co-stimulatory molecules are critical for T cell activation and ensure that T cells only respond to antigens presented in the context of an immune response (e.g., infection).
    • CD28 is a major co-stimulatory receptor that binds to CD80 and CD86 on APCs.
    • CD58 is a backup co-stimulatory molecule that can bind to CD2 on T cells.

    Immunological Synapse

    • The purpose of the immunological synapse is to facilitate communication and interaction between T cells and antigen-presenting cells (APCs).

    T-Cell Signal Transduction

    • T-cell signal transduction is the process of transmitting signals from the cell surface to the inside of the cell.
    • ITAMs are signaling motifs that play a significant role in T-cell signaling.
    • Specific signals are needed to activate T cells and initiate their functions.
    • Different signals can trigger anergy (a state of non-responsiveness) or effector function.

    IL-2 Importance

    • IL-2 is a cytokine crucial for the proliferation and differentiation of activated naive T cells.
    • Naive T cells and activated T cells express different forms of the IL-2 receptor.

    CD4+ & CD8+ Maturation

    • CD4+ and CD8+ T cell maturation differ in their activation pathways and roles in the immune response.

    CD4+ Subtypes

    • There are five subtypes of CD4+ T cells:
      • TH1 cells induce macrophage activation.
      • TH2 cells have an anti-inflammatory phenotype.
      • TH17 cells promote inflammation.
      • Treg cells suppress autoreactive T cells.
      • TFH cells help B cells produce antibodies.

    Co-stimulatory Molecules and Signals

    • Co-stimulatory molecules provide secondary signals necessary for T-cell activation.
    • CD28 is a significant co-stimulatory molecule.
    • CD58 acts as a back-up co-stimulatory molecule that binds with CD2.

    Memory T Cells

    • Some CD4+ T cells enter a memory state.
    • Memory T cells express increased CD28 and decreased L-selectin.
    • Memory T cells are more likely to respond rapidly to CD80/86 displayed by APCs.
    • Memory T cells home to sites of inflammation rather than lymph nodes.

    CD8+ Memory Cells

    • CD8+ T cells can also form memory cells.
    • The expression of CD58 is increased in memory T cell connections.

    T Cell Killing

    • T cell killing involves a process of granular exocytosis that releases cytotoxic molecules, such as perforin and granzymes.
    • The release of these molecules leads to apoptosis (programmed cell death) of the target cell.
    • Cytotoxic CD8 T cells can kill multiple infected target cells in succession.
    • Effector T cells utilize integrin VLA-4 to home to inflamed tissues.
    • Co-stimulatory signals are crucial for the activation of naive T cells but not for activating effector T cells.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    8_ T-CELL ACTIVATION & EFFECTOR FUNCTION.pptx

    Description

    This quiz explores the concepts of T cell anergy, activation of naive T cells, and the differentiation of naive CD4 T cells into various effector subtypes. It examines the role of cytokines, particularly interleukin-2, in T cell responses and the functions of different CD4 T cell types.

    More Quizzes Like This

    Innate Immune Response and T Cell Activation
    5 questions

    Innate Immune Response and T Cell Activation

    RichAgate avatar
    RichAgate
    Naïve T Cell Activation Quiz
    23 questions

    Naïve T Cell Activation Quiz

    ConvincingFluorite avatar
    ConvincingFluorite
    B Cell Activation and Differentiation
    23 questions

    B Cell Activation and Differentiation

    sg19 avatar
    sg19
    B Cell Activation Fundamentals
    23 questions

    B Cell Activation Fundamentals

    PatriLavender avatar
    PatriLavender
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser