Immunology Lecture 2-5
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Questions and Answers

Which of the following cytokines is NOT involved in the differentiation of Th17 cells?

  • IFN-γ (correct)
  • IL-17
  • TGF-β
  • IL-22

    • What is the primary function of Th2 cells?

  • Suppressing immune responses
  • Fighting extracellular pathogens
  • Killing target cells
  • Providing help for B cells (correct)

    • Which type of T cell is involved in suppressing stimulatory activity of APCs?

  • Th17
  • Th2
  • Treg (correct)
  • Th1

    • What is the primary function of CD8+ T cells?

    <p>Killing target cells</p> Signup and view all the answers

    Which cytokine is involved in the differentiation of Th1 cells?

    <p>IFN-γ</p> Signup and view all the answers

    What is the role of TGF-β in the differentiation of Treg cells?

    <p>Inducing the differentiation of Treg cells</p> Signup and view all the answers

    Which cells display peptides in the context of highly polymorphic MHC molecules?

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

    What is required for the activation of T cells?

    <p>Two signals</p> Signup and view all the answers

    What is the primary function of CD8 T cells?

    <p>To recognise and kill virus-infected or cancerous cells</p> Signup and view all the answers

    What is required for the activation of CD4 T cells?

    <p>Two signals, one from the T cell receptor and one from a co-stimulatory molecule</p> Signup and view all the answers

    What is the function of MHC class I molecules?

    <p>To present antigens to CD8 T cells</p> Signup and view all the answers

    What is the result of T cell receptor genes undergoing rearrangements?

    <p>The creation of a highly diverse repertoire of T cell receptors</p> Signup and view all the answers

    What is the function of co-stimulatory molecules such as CD28 and CD86?

    <p>To provide the second signal for T cell activation</p> Signup and view all the answers

    What is the difference between MHC class I and II molecules?

    <p>MHC class I molecules present antigens to CD8 T cells, while MHC class II molecules present antigens to CD4 T cells</p> Signup and view all the answers

    What is the result of the interaction between the T cell receptor and MHC molecules?

    <p>The recognition of peptides by T cells</p> Signup and view all the answers

    What is the characteristic of T cell receptors?

    <p>They are composed of two chains joined by disulphide bonds</p> Signup and view all the answers

    What is the function of antigen-presenting cells (APCs) such as monocytes, macrophages, and dendritic cells?

    <p>To present antigens to T cells</p> Signup and view all the answers

    What is the result of the activation of CD4 T cells?

    <p>The activation of macrophages and the production of cytokines</p> Signup and view all the answers

    Study Notes

    T Cell Antigen Recognition

    • Peptides are displayed by cells in the context of highly polymorphic MHC molecules.
    • MHC molecules are highly polymorphic, with MHC I and II having different structures and functions.
    • MHC I is expressed on all nucleated cells, associates with β2 microglobulin, and is endogenously expressed.
    • MHC II is expressed on specialized antigen-presenting cells (APCs), including monocytes, macrophages, dendritic cells, and B lymphocytes.

    Sources of Peptides Loaded into MHC Class I and II

    • MHC class I is loaded with peptides from viral proteins and endogenous proteins.
    • MHC class II is loaded with peptides from exogenous antigens.

    T Cells Recognise Peptides with Their T Cell Receptors

    • T cells are defined by expression of the T cell receptor (TCR), which is a membrane-bound heterodimer.
    • TCR consists of two chains (α and β) joined by disulfide bonds, with variable and constant domains.
    • TCR genes undergo rearrangements from germline before translation.

    Two Main Classes of ab T Cell

    • CD8+ T cells (cytotoxic T cells) recognise peptides presented by MHC I.
    • CD4+ T cells (helper T cells) recognise peptides presented by MHC II.

    Activation of T Cells Requires Two Signals

    • Signal 1: TCR recognises peptide-MHC complex.
    • Signal 2: Co-stimulation by CD28 and CD86, which is upregulated on APCs by danger signals (infection, inflammation).

    CD8 T Cells: Cytotoxic Lymphocytes (CTL)

    • CD8+ T cells are cytotoxic cells that can kill target cells, such as virus-infected cells or cancerous cells.

    Activated CD4 Cells Can Differentiate into Different Kinds of Effector T Cells

    • CD4+ T cells can differentiate into different types of helper T cells, including Th1, Th2, Th17, and Treg cells.
    • Each type of helper T cell has distinct functions, such as producing different cytokines and providing help to different cells.

    CD4+ T Cell Subsets

    • Th1 cells: produce IFN-γ and IL-2, help activate CD8+ T cells and macrophages.
    • Th2 cells: produce IL-4, IL-5, and IL-13, help activate B cells.
    • Th17 cells: produce IL-17, IL-21, and IL-22, help fight extracellular pathogens.
    • Treg cells: produce TGF-β and IL-10, suppress immune responses.

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    Description

    This quiz covers the topics of innate immune protection, antibody and lymphocyte diversity, T cells, MHC, tolerance, and T cell effector functions in immunology lectures 2-5.

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