Immunology and T Cell Function
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Questions and Answers

What is the role of T cells in relation to macrophages?

  • T cells stimulate macrophages to kill ingested microbes. (correct)
  • T cells inhibit macrophage activity.
  • T cells prevent macrophages from maturing.
  • T cells directly kill the microbes themselves.

    • Which type of cell is primarily targeted by intracellular viruses?

  • Epithelial cells. (correct)
  • Phagocytic cells.
  • B cells.
  • Neutrophils.

    • Which of the following is NOT an example of an intracellular microbe?

  • Streptococcus pneumoniae. (correct)
  • Listeria monocytogenes.
  • Cryptococcus neoformans.
  • Mycobacteria.

    • What is the main function of T cells in humoral immune responses?

    <p>To aid in the production of antibodies.</p> Signup and view all the answers

    Which of the following microbes can survive within phagolysosomes?

    <p>Legionella pneumophila.</p> Signup and view all the answers

    How do intracellular bacteria like Mycobacteria evade the immune response?

    <p>By escaping into the cytoplasm.</p> Signup and view all the answers

    Which protozoan parasite is mentioned as capable of being targeted by T cell-mediated immunity?

    <p>Leishmania.</p> Signup and view all the answers

    What are the roles categorized for T lymphocytes?

    <p>Activation of phagocytes, killing of infected cells, and support for B cell functions.</p> Signup and view all the answers

    What is the primary function of phagocytes in the immune response?

    <p>To ingest and destroy microbes</p> Signup and view all the answers

    What type of cells can T lymphocytes communicate with during an immune response?

    <p>Infected host cells</p> Signup and view all the answers

    How do T cells recognize the antigens of microbes?

    <p>By detecting antigens displayed by MHC molecules</p> Signup and view all the answers

    What triggers the activation of naive T lymphocytes?

    <p>Antigen recognition in peripheral lymphoid organs</p> Signup and view all the answers

    Which of the following describes obligate intracellular parasites?

    <p>They are dependent on host cells for survival and replication.</p> Signup and view all the answers

    What is the role of dendritic cells in the immune response?

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

    What mechanism do effector T cells utilize to eliminate microbes?

    <p>Amplifying the immune response through cytokines</p> Signup and view all the answers

    What is a characteristic of memory T cells?

    <p>They can respond more rapidly upon re-exposure to an antigen.</p> Signup and view all the answers

    What is the main role of CD4+ T cells in the immune response?

    <p>To help B cells produce antibodies</p> Signup and view all the answers

    Which cytokine is essential for T cell activation and proliferation?

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

    How do effector T cells migrate to the site of infection?

    <p>By binding to activated endothelial cells</p> Signup and view all the answers

    What distinguishes CD8+ cytotoxic T lymphocytes (CTLs) from CD4+ T cells?

    <p>Their primary role in killing infected cells</p> Signup and view all the answers

    What fate do some activated CD4+ T cells undergo after their initial activation?

    <p>They become memory T cells and circulate indefinitely</p> Signup and view all the answers

    What triggers the activation of endothelial cells during infection?

    <p>Cytokines produced in response to infection</p> Signup and view all the answers

    What is the primary function of memory T cells?

    <p>To provide rapid response upon re-exposure to antigens</p> Signup and view all the answers

    In addition to helping B cells, what other function do CD4+ T cells perform?

    <p>They activate phagocytes</p> Signup and view all the answers

    What role does PKCθ play in T cell activation?

    <p>It activates NF-κB by phosphorylating IκB.</p> Signup and view all the answers

    Which metabolic process do activated T cells predominantly switch to?

    <p>Aerobic glycolysis</p> Signup and view all the answers

    What is initiated by the destruction of IκB during T cell activation?

    <p>Movement of NF-κB to the nucleus</p> Signup and view all the answers

    What is the function of phosphatidylinositol-3 kinase (PI-3 kinase) in T cell signaling?

    <p>Generates PIP3 needed for downstream signaling.</p> Signup and view all the answers

    Upon T cell activation, how does glucose utilization change?

    <p>It increases significantly.</p> Signup and view all the answers

    What is one of the key roles of the Akt (protein kinase B) during T cell activation?

    <p>It stimulates expression of antiapoptotic proteins.</p> Signup and view all the answers

    Which signaling pathway can initiate the PI-3 kinase/Akt pathway?

    <p>Through multiple immune receptors including CD28.</p> Signup and view all the answers

    What type of protein does PKC activate through its signaling pathway?

    <p>Transcription factors such as NF-κB.</p> Signup and view all the answers

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

    <p>Facilitating clonal expansion of T cells</p> Signup and view all the answers

    During an immune response, what happens to the number of T cells specific for the antigen?

    <p>It undergoes clonal expansion followed by contraction</p> Signup and view all the answers

    What is the approximate frequency of CD8+ T cells specific for any one microbial protein antigen before infection?

    <p>1 in 1,000,000</p> Signup and view all the answers

    What does clonal contraction refer to in T cell responses?

    <p>The elimination of excess T cells after an immune response</p> Signup and view all the answers

    How does the number of lymphocytes in humans compare to the findings in studies of inbred mice?

    <p>They are about 1000 times greater</p> Signup and view all the answers

    What is one function that IL-2 is essential for besides T cell growth?

    <p>Maintenance of regulatory T cells</p> Signup and view all the answers

    What characterizes the functional responses of T lymphocytes during an immune response?

    <p>Gradual expansion followed by a contraction phase</p> Signup and view all the answers

    What is the significance of memory T cells in the immune response?

    <p>They allow for a faster response upon re-exposure to the same antigen</p> Signup and view all the answers

    What type of molecules are involved in the elimination of antigens?

    <p>Membrane molecules</p> Signup and view all the answers

    Which component of the antibody structure is primarily responsible for antigen binding?

    <p>Light chain</p> Signup and view all the answers

    What is the function of the Fc region in an antibody?

    <p>Binding to complement proteins</p> Signup and view all the answers

    Which of the following best describes the Fab region of an antibody?

    <p>Composed of both heavy and light chains</p> Signup and view all the answers

    What are complementarity determining regions (CDRs) responsible for?

    <p>Determining antibody specificity</p> Signup and view all the answers

    What structural feature allows antibodies to form disulfide bonds?

    <p>Ig domain</p> Signup and view all the answers

    Which antibody is primarily found in a membrane-bound form on B cells?

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

    Which region of the antibody connects the Fab and Fc portions?

    <p>Hinge region</p> Signup and view all the answers

    What characterizes the structural domain variations in antibodies?

    <p>Variable and constant regions</p> Signup and view all the answers

    In antibody structure, what does the term 'tail piece' refer to?

    <p>The end of the Fc region</p> Signup and view all the answers

    The heavy chains of antibodies are characterized by which feature?

    <p>Multiple constant regions</p> Signup and view all the answers

    Which combination of antibody classes is correct for their specific functions?

    <p>IgA - Enhancing phagocytosis, IgE - Allergic reactions</p> Signup and view all the answers

    What is the role of the CH domains in antibodies?

    <p>Determining the type of antibody</p> Signup and view all the answers

    The presence of multiple immunoglobulin domains in antibodies contributes to which of these properties?

    <p>More efficient antigen binding</p> Signup and view all the answers

    Study Notes

    Antigen Recognition in the Adaptive Immune System

    • Antigen receptors are crucial for lymphocyte maturation and adaptive immune responses.
    • Naive lymphocytes recognize antigens to initiate responses, while effector T cells and antibodies carry out the functions.
    • B cells express membrane-bound antibodies (BCRs), and T cells express T cell receptors (TCRs).
    • BCRs recognize a wide range of antigens—shapes, conformations, macromolecules (proteins, lipids, carbs, nucleic acids).
    • TCRs are specific for peptides bound to major histocompatibility complex (MHC) molecules.

    Lymphocyte Repertoires

    • Lymphocyte clones recognize specific antigens.
    • Each clone's receptor is unique.
    • The combination of all lymphocyte clones is known as the immune repertoire.
    • The repertoire is vast.
    • Receptor structure transmits biochemical signals that are similar across all lymphocytes but irrelevant to specificity.

    Questions about Lymphocyte Recognition

    • How do lymphocyte receptors recognize diverse antigens and transmit activating signals?
    • What differences exist in the recognition properties of receptors (BCRs and TCRs)?
    • How is the vast diversity of lymphocyte receptor structures generated?

    Antigen Recognition by B Cells

    • B cell receptors, like antibodies, can bind diverse molecules.
    • Antibodies bind antigens with variable domains and constant domains.

    Antigen Recognition by T Cells

    • T cell receptors (TCRs) recognize antigens presented by MHC molecules.
    • TCRs are similar to immunoglobulin (Ig) V and C regions in structure.
    • TCR diversity stems from gene recombination.

    Antibody Structure

    • Antibodies are composed of two identical heavy chains and two identical light chains.
    • The chains assemble into a Y-shaped molecule linked by disulfide bonds.
    • Variable regions (VH and VL) form the antigen-binding site, while constant regions (CH and CL) dictate effector functions.

    Additional Notes

    • Antigen receptors are clonally distributed, meaning each lymphocyte clone possesses a unique receptor.
    • Antibodies can exist as membrane-bound receptors or secreted proteins. TCRs only exist as membrane receptors.

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    Related Documents

    Chapter 4+5: Antigen Recognition in the Adaptive Immune System PDF

    Description

    This quiz explores the intricate roles of T cells in the immune response, their interactions with other immune cells like macrophages and dendritic cells, and the mechanisms they employ against intracellular pathogens. Test your knowledge on how T cells recognize antigens, their functions, and the types of cells they target during infections.

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