Immunology Quiz: T Cells and Avidity
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Questions and Answers

What is primarily executed by cytotoxic T-lymphocytes (CTLs)?

  • Lysis of infected cells (correct)
  • Production of antibodies
  • Phagocytosis of pathogens
  • Presentation of antigens to helper T cells

    • What cells are responsible for the presentation of antigens via MHC Class II molecules?

  • All nucleated cells
  • Plasma cells
  • Antigen-presenting cells (APCs) (correct)
  • B cells and platelets

    • Which type of antigens do MHC Class II molecules primarily bind to?

  • Endogenous antigens
  • Exogenous antigens (correct)
  • Neoantigens
  • Self-antigens

    • Which of the following is a function of the proteasome in the immune system?

    <p>Degradation of unwanted/damaged proteins</p> Signup and view all the answers

    What type of T cell interacts with peptide-MHC I complexes?

    <p>CD8+ cytotoxic T cells</p> Signup and view all the answers

    What kind of fragments do MHC Class I molecules bind to?

    <p>Endogenous antigen fragments</p> Signup and view all the answers

    Which statement about antibodies secreted by plasma cells is correct?

    <p>They recognize specific epitopes expressed by pathogens.</p> Signup and view all the answers

    What is a major characteristic of MHC Class I molecules compared to MHC Class II?

    <p>They bind to endogenous antigens.</p> Signup and view all the answers

    Which of the following statements about PEG-ylicated recombinant IFNs and ILs is true?

    <p>They enhance thermal stability and prolong circulation half-lives.</p> Signup and view all the answers

    What is the primary role of Interleukin-2 (IL-2)?

    <p>Stimulates growth and activation of T, B, and NK cells</p> Signup and view all the answers

    What is a key action of granulocyte colony-stimulating factor (G-CSF)?

    <p>Increases the production of neutrophils</p> Signup and view all the answers

    Which type of cells primarily produce Interleukin-11 (IL-11)?

    <p>Fibroblasts and bone marrow stromal cells</p> Signup and view all the answers

    What is the main purpose of hematopoietic growth factors like erythropoietin (EPO)?

    <p>To restore hematopoietic cells after chemotherapy</p> Signup and view all the answers

    Which of the following effects is associated with IL-11?

    <p>Induces megakaryocyte maturation</p> Signup and view all the answers

    How do branched chains of PEG enhance the properties of recombinant cytokines?

    <p>By protecting proteins from proteolytic degradation</p> Signup and view all the answers

    Which immunomodulatory property is directly attributed to IL-2?

    <p>Acts specifically on cells with IL-2 receptors</p> Signup and view all the answers

    What is the role of avidity in antibody function?

    <p>It measures the strength of an antibody's binding to its target.</p> Signup and view all the answers

    What structure on T cells is responsible for antigen recognition?

    <p>T Cell Receptor (TCR)</p> Signup and view all the answers

    What is true about the ITAMs present in TCR complexes?

    <p>ITAMs undergo phosphorylation upon antigen binding.</p> Signup and view all the answers

    Which component of the T Cell Receptor complex mediates signal transduction?

    <p>CD3 adapter proteins</p> Signup and view all the answers

    What is the function of the constant region in T Cell Receptors?

    <p>To form disulfide bonds between chains.</p> Signup and view all the answers

    Which of the following describes a key feature of the T Cell Receptor?

    <p>It consists of both variable and constant regions.</p> Signup and view all the answers

    How many ITAMs does the T Cell Receptor complex typically contain?

    <p>10</p> Signup and view all the answers

    What initiates the series of downstream signaling events in T cell activation?

    <p>Phosphorylation of tyrosine residues in ITAMs.</p> Signup and view all the answers

    What is the primary focus of immunotherapy?

    <p>Intervening in the immune system to treat disease</p> Signup and view all the answers

    Which of the following is an example of a therapeutic strategy in immunotherapy?

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

    What role do interferons play in the immune response?

    <p>Promoting an antiviral state in neighboring cells</p> Signup and view all the answers

    Which cytokines are primarily involved in regulating immunity and inflammation?

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

    What is the primary function of colony-stimulating factors (CSF)?

    <p>Stimulating cellular division and differentiation of blood cells</p> Signup and view all the answers

    What type of immunotherapy involves the use of agents that reduce immune responses?

    <p>Cytokine suppression</p> Signup and view all the answers

    Which cells primarily produce interleukins?

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

    Which of the following cytokines is known for promoting an antiviral state?

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

    What is one of the main functions of PD-L1/PD-L2 in the context of cancer immunotherapy?

    <p>To suppress T cell activity</p> Signup and view all the answers

    Which of the following is a PD-1 inhibitor used in the treatment of certain cancers?

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

    What is a primary limitation of checkpoint inhibitors in cancer treatment?

    <p>They can cause immune-related adverse events.</p> Signup and view all the answers

    How do cancer vaccines assist in cancer management?

    <p>By potentiating the patient’s own immune system</p> Signup and view all the answers

    What is a characteristic of the therapeutic vaccines mentioned in the context of cancer?

    <p>They aim to reactivate the immune system against tumors.</p> Signup and view all the answers

    Which type of cancer vaccine includes tumor cells to induce T cell responses?

    <p>Tumor cell vaccine</p> Signup and view all the answers

    What is a reason why not all cancer patients respond to checkpoint inhibitors?

    <p>The microenvironment of tumors is complex.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of checkpoint inhibitors?

    <p>They directly kill cancer cells.</p> Signup and view all the answers

    Study Notes

    Avidity and Antibody Binding

    • Avidity refers to the overall strength with which an antibody binds to its target, particularly when multiple epitopes are present.
    • This concept is critical for antibodies such as IgM, which can bind to several antigenic sites.

    T Cells and T Cell Receptor (TCR) Complex

    • T Cell Receptors (TCR) are cell surface receptors essential for antigen recognition, composed of α and β chains.
    • Each TCR has two extracellular domains: a variable (V) region for antigen binding and a constant (C) region that forms disulfide bonds.
    • TCRs lack a functional cytoplasmic tail for signaling; instead, they associate with CD3 adapter proteins (CD3εγ, CD3εδ, CD3ζζ) for signal transduction.
    • Each TCR complex contains 10 immunoreceptor tyrosine-based activation motifs (ITAMs), initiating signaling upon antigen binding.

    Comparison of TCR and Antibodies

    • TCRs engage in cell-mediated immunity executed by cytotoxic T-lymphocytes (CTLs), while antibodies drive the humoral immune response through plasma cells.
    • Antibodies bind specific epitopes on pathogens and can engage effector cells, such as macrophages and neutrophils, via Fc receptors.

    Antigen Presentation and MHC Class I & II

    • Antigen-presenting cells (APCs) process pathogens through phagocytosis, breaking them down into peptide fragments presented on MHC (Major Histocompatibility Complex) molecules.
    • MHC Class I molecules are expressed on all nucleated cells, presenting endogenous antigens to CD8+ CTLs.
    • MHC Class II molecules are expressed mainly by APCs (e.g., macrophages, dendritic cells) and present exogenous antigens to CD4+ helper T cells.

    Proteasome Function

    • The proteasome degrades unwanted or damaged proteins into peptide fragments (~15 amino acids long) through proteolysis, a crucial process for antigen processing.

    Immune Responses

    • CD8+ CTLs respond specifically to peptide-MHC I complexes, while CD4+ helper T cells interact with peptide-MHC II complexes, ensuring diverse adaptive immune responses.

    Immunotherapy Overview

    • Immunotherapy involves modifying the immune system to treat diseases, including activation (e.g., vaccines) and suppression of immune responses.
    • Therapeutic strategies include the use of cytokines, antibodies, T cells, and cancer vaccines.

    Cytokines in Immunotherapy

    • Cytokines play significant roles in both innate and adaptive immunity, influencing inflammation and hematopoiesis.
    • Recombinant cytokines and anti-cytokine therapies treat various conditions, from infections to cancer.

    Types of Cytokines

    • Interferons: Produced in response to viral infections, promoting antiviral states.
    • Interleukins: Regulate immune cell growth and response (e.g., IL-2 stimulates T cell growth).
    • Colony Stimulating Factors (CSF): Stimulate blood cell production from bone marrow.
    • Chemokines: Induce chemotaxis and activation of leukocytes.

    PEGylated Cytokines

    • PEG (polyethylene glycol) is used to enhance cytokine stability and circulation time while reducing immunogenicity, leading to controlled drug release.

    Hematopoietic Growth Factors

    • Regulate differentiation of pluripotent stem cells into active immune cells; used to restore cell deficiencies post-chemotherapy or radiation.

    Checkpoint Inhibitors

    • Target immune inhibitory pathways to unmask T cell activity against tumors (e.g., PD-1 and PD-L1 inhibitors).
    • Limitations include variable patient responses, transient efficacy, and potential immune-related side effects.

    Cancer Vaccines

    • Aimed at reactivating the patient’s immune response against cancer, cancer vaccines can be categorized into three types: tumor cell vaccines, dendritic cell vaccines, and more.
    • These vaccines are designed to provoke a specific immune targeting of tumor antigens to control or eliminate cancer cells.

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    Description

    Test your knowledge on the avidity of antibodies and the function of T cell receptors in immune response. This quiz covers key concepts regarding antibody binding strengths, T lymphocytes, and the composition of T cell receptors. Perfect for students studying immunology or related fields.

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