T Cell Development and Activation: Part 1
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Questions and Answers

What is the primary advantage of utilising highly specific antigen receptors in adaptive immunity?

  • Recognition of stereotypical PAMPs
  • Induction of immunological tolerance
  • Elimination of immunological memory
  • Recognition of pathogens lacking stereotypical PAMPs (correct)

    • What is the outcome of the resolution phase of an immune response?

  • Expansion of pathogen-specific cells
  • Maturation of T cells
  • Induction of immunological tolerance
  • Contraction of the immune response (correct)

    • What is the primary role of T cells in immune responses?

  • Orchestration of immune responses (correct)
  • Production of antibodies
  • Recognition of PAMPs
  • Presentation of antigens to B cells

    • What is the outcome of T cell activation?

    <p>T cell differentiation</p> Signup and view all the answers

    What is the primary mechanism of adaptive immunity?

    <p>Antigen-specific recognition</p> Signup and view all the answers

    What is the primary function of CD4+ and CD8+ T cells?

    <p>Helper function and cytotoxicity</p> Signup and view all the answers

    What is the primary function of cytotoxic T cells?

    <p>To kill infected cells</p> Signup and view all the answers

    What is the main difference between effector and memory T cells?

    <p>Effector T cells are activated upon antigen recognition, while memory T cells are not</p> Signup and view all the answers

    What is the role of antigen-presenting cells in T cell activation?

    <p>To present antigens to helper T cells, which then activate cytotoxic T cells</p> Signup and view all the answers

    What is the significance of MHC class I in T cell activation?

    <p>It is involved in the recognition of antigens by cytotoxic T cells</p> Signup and view all the answers

    What is the primary function of helper T cells?

    <p>To assist other white blood cells in the immune response</p> Signup and view all the answers

    What is the difference between naïve and effector T cells?

    <p>Naïve T cells are not activated, while effector T cells are activated</p> Signup and view all the answers

    What is the primary function of γδ T cells in the immune system?

    <p>To directly kill infected cells</p> Signup and view all the answers

    What determines the differentiation of T cells into specific subsets?

    <p>The cytokine environment created by the APC and other cells</p> Signup and view all the answers

    What is the term used to describe the process of T cell differentiation into specific subsets based on the cytokine environment?

    <p>T cell polarisation</p> Signup and view all the answers

    What is the function of Th2 cells?

    <p>To combat extracellular parasites and helminths</p> Signup and view all the answers

    What is the primary function of Tregs?

    <p>To regulate and inhibit immune responses</p> Signup and view all the answers

    What is the role of the third signal in T cell activation?

    <p>To direct T cell differentiation into specific subsets</p> Signup and view all the answers

    What is the primary function of T-Bet in Th1 and Th2 cross-regulation?

    <p>To repress the expression of GATA-3 and the TH2 effector cytokines</p> Signup and view all the answers

    Which of the following cytokines is involved in the differentiation of Th1 cells?

    <p>IL-12</p> Signup and view all the answers

    What is the primary function of GATA-3 in Th1 and Th2 cross-regulation?

    <p>To up-regulate the synthesis of IL-4 and IL-5</p> Signup and view all the answers

    Which of the following cell subsets is involved in B cell activation and Ab production?

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

    What is the primary function of IL-4 in Th1 and Th2 cross-regulation?

    <p>To promote the expression of GATA-3</p> Signup and view all the answers

    Which of the following cytokines is involved in the differentiation of Th17 cells?

    <p>IL-6</p> Signup and view all the answers

    What is the primary requirement for CD8+ T cell activation, in addition to the two signals provided by the APC?

    <p>More co-stimulation than Th cells, usually provided by effector CD4+ Th cells</p> Signup and view all the answers

    How do CD4+ Th cells help activate CD8+ T cells?

    <p>By producing IL-2 and expressing CD40L</p> Signup and view all the answers

    What is the consequence of the requirement for CD8+ T cells to be activated by related antigens presented by BOTH MHC I and MHC II on the same APC?

    <p>Most viruses are unable to activate CD8+ T cells</p> Signup and view all the answers

    What is the role of CD40L in CD8+ T cell activation?

    <p>It binds to CD40 on the APC, enhancing CD80/CD86 expression</p> Signup and view all the answers

    Why are CD4+ Th cells necessary for CD8+ T cell activation?

    <p>They provide co-stimulation for CD8+ T cell activation</p> Signup and view all the answers

    What is the consequence of CD4+ Th cells recognizing related antigen on the APC?

    <p>CD4+ Th cells are activated and produce IL-2 and CD40L</p> Signup and view all the answers

    T cell activation requires only one signal from the antigen-presenting cell.

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

    Adaptive immunity can only be achieved through natural exposure to pathogens.

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

    CD4+ T cells are involved in the humoral immune response.

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

    The primary role of T cells is to recognize and eliminate infected cells and present antigens to B cells.

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

    Effector-memory T cells are like naïve T cells upon activation.

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

    The resolution phase of an immune response results in the expansion of immune cells.

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

    T cells can recognize pathogens with stereotypical PAMPs.

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

    CD4+ T cells are involved in the destruction of intracellular pathogens.

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

    CD8+ T cells can recognize antigens presented by antigen-presenting cells through MHC class II.

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

    Antigen recognition is the only step required for T cell activation.

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

    Naïve T cells are a type of memory T cell.

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

    T cell activation only occurs in peripheral infected organs.

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

    Co-stimulatory molecules are necessary for the activation of CD8+ T cells but not CD4+ T cells.

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

    CD8+ T cells can be activated by a single signal provided by the APC.

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

    The protein Lck is involved in the activation of T cells through its interaction with ITAM.

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

    CD40L binds to CD40L on the APC, which stimulates it to make more costimulatory CD80/CD86.

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

    The production of cytokine, mainly IL-2, is induced by the first signal of T cell activation.

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

    CD8+ T cells can be activated by unrelated antigens presented by the APC.

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

    CD4+ Th cells help activate CD8+ T cells by providing cytokines and CD28.

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

    CD80 and CD86 are co-stimulatory molecules found in mice.

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

    T cell activation results in the suppression of transcription factors and gene expression.

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

    CD80/CD86 is the murine equivalent of human B7.1/B7.2.

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

    The clonal expansion of T cells is a result of antigen recognition by the TCR/MHC interaction.

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

    Viruses are naturally trophic for dendritic cells, allowing for efficient activation of CD8+ T cells.

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

    Almost all effector T cells die once the antigen is eliminated.

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

    Cross presentation of exogenous antigens to MHC-I is important for CD4+ T cell activation

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

    CD80/86-CD28 is enough for CD8+ T cell activation

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

    MHC class I molecules only present peptides from endogenous antigens

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

    The third signal in T cell activation is antigen recognition

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

    Th1 cells produce TNFα/IFNγ and mediate humoral immune responses

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

    Study Notes

    • T cell development and activation involves five key learning outcomes: the role of T cells in immune responses, the maturation and selection process for CD4+ and CD8+ T cells, stages and development of T cell-mediated immunity (CMI), the 2 steps to T cell activation, and the 3rd signal and T cell differentiation.

    • Adaptive immunity is an immune response that becomes more powerful following repeated encounters with the same antigen, utilizing highly specific antigen receptors that allow for recognition of pathogens lacking stereotypical PAMPs, highly specific responses for a given pathogen, and immunological memory.

    • The advantages of adaptive immunity include highly diverse populations of cells, pathogen-specific cells expanding and improving in the repertoire, and resolution (contraction) and memory.

    • Specific immunity can be achieved through natural exposure (e.g., chickenpox) or artificially by vaccination (e.g., MMR/COVID).

    • T cells are long-lived and can be reactivated, making them essential for immune responses.

    • T cell terminology includes naïve, effector, and memory T cells, with naïve T cells being the precursors of effector T cells.

    • Effector T cells are further divided into effector-memory and central memory T cells, with effector-memory T cells having a more rapid response to antigen.

    • The magnitude of T cell response involves the activation of naïve T cells, the expansion of effector T cells, and the contraction and homeostasis of memory T cells.

    • T cell activation requires two signals: antigen recognition (MHC/antigen-TCR) and costimulation (CD80/86-CD28), with the 3rd signal (cytokine environment) dictating the type of T effector cell.

    • CD4+ T cells (Th cells) recognize antigen presented by MHC class II and assist other white blood cells, while CD8+ T cells (Tc cells) recognize antigen presented by MHC class I and kill infected cells.

    • The 3rd signal (cytokine environment) directs T cell differentiation into different subsets, including Th1, Th2, Th17, Tregs, and Tfh cells.

    • Cytokines produced by antigen-presenting cells (APCs) and other cells create a cytokine environment that influences T cell differentiation.

    • Differentiation of Th cells is induced by different cytokines, producing different types of effector CD4+ T cells, each with distinct functions.

    • Th1 cells are involved in anti-inflammatory responses, peripheral tolerance, and bacterial infections, while Th2 cells are involved in pro-inflammatory responses, B cell activation, and helminth infections.

    • Th17 cells are involved in pro-inflammatory responses, bacterial infections, and autoimmune diseases.

    • Tregs are involved in anti-inflammatory responses, peripheral tolerance, and autoimmune diseases.

    • TfH cells are involved in B cell activation and antibody production.

    • Cross-presentation of exogenous antigens to MHC-I is important for CD8+ T cell (CTL) activation, which requires Th help and CD40-CD40L interaction.

    • The dynamics of T cell response involve antigen recognition, activation, antigen elimination, contraction/homeostasis, and memory.

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    T Cell Development and Activation: Part 1 PDF

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    Test your knowledge on the role of T cells in immune responses, their maturation and selection process, and the stages of T cell mediated immunity. Learn about the two steps to T cell activation and the third signal in T cell differentiation.

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