W3-1 antigen presentation and t-lymphocyte biology
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Questions and Answers

What is the purpose of MHC-I-restricted antigen presentation?

  • Providing help for other leukocytes involved in an immune response
  • Promoting inflammation
  • Identifying cells that must be destroyed (correct)
  • Regulating the immune system

    • Which cells respond to MHC-II-restricted antigen presentation?

  • Treg cells
  • CD8 T lymphocytes
  • TH2 cells (correct)
  • TH1 cells

    • What is the function of memory T lymphocytes?

  • Initiating an immune response
  • Killing infected or tumor cells
  • Regulating immune responses
  • Providing long-term immunity (correct)

    • What is the source of peptides for MHC-I molecules?

    <p>Endogenous proteins in the cytosol</p> Signup and view all the answers

    What are super-antigens and how do they work?

    <p>Antigens that stimulate a large proportion of T cells non-specifically</p> Signup and view all the answers

    What is the functional consequence of a missing MHC-I molecule?

    <p>Impaired killing of infected or tumor cells</p> Signup and view all the answers

    Which cells bear MHC-I and MHC-II molecules?

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

    How are proteins processed for antigen presentation?

    <p>Transfer to the endoplasmic reticulum for peptide loading onto MHC molecules</p> Signup and view all the answers

    What is the structure of the MHC-I molecule?

    <p>Two identical alpha chains and one beta-2 microglobulin chain</p> Signup and view all the answers

    How do T lymphocytes migrate?

    <p>By chemotaxis towards chemokine gradients</p> Signup and view all the answers

    What are the properties of the different T lymphocyte subsets?

    <p>They exhibit diverse T cell receptors and distinct effector functions</p> Signup and view all the answers

    What is the function of calnexin in the antigen presentation pathway?

    <p>To keep the MHC class I α chain in an inactive, partially folded state</p> Signup and view all the answers

    What protein dissociates from the MHC class I α chain upon binding of β2microglobulin?

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

    What is the term given for extracellular material that ends up being presented by MHC-I molecules on a cell’s surface?

    <p>Cross-presentation</p> Signup and view all the answers

    What is the role of tapasin in the MHC class I molecule pathway?

    <p>To bridge TAP1 with the MHC class I molecule and possibly stabilize the MHC class I α chain:β2m heterodimer in the absence of peptide</p> Signup and view all the answers

    What is required in addition to MHC-restricted antigen presentation to achieve effector functions in T lymphocytes?

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

    What delivers the survival signal to T lymphocytes in the form of surface co-stimulatory molecules CD80/86?

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

    Which proteins form the CD3 signaling complex in the TCR?

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

    What is the function of ERp57 in association with calcineurin and calreticulin?

    <p>To properly fold the MHC class I α chain through the isomerisation of disulfide bonds present on the heavy chain</p> Signup and view all the answers

    What protein binds to the transmembrane chaperone protein calnexin and the enzyme ERp57?

    <p>MHC class I α chain (heavy chain)</p> Signup and view all the answers

    Where can exogenous peptides leak into, for display by MHC Class I molecules?

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

    What leads to high enough pAPC CD80/CD86 expression to activate CD8 cells into becoming cytotoxic T lymphocytes (CTLs)?

    <p>CD40L present on activated CD4 cells (TH1)</p> Signup and view all the answers

    What is the purpose of MHC-II-restricted antigen presentation?

    <p>Select and activate CD4 lymphocytes</p> Signup and view all the answers

    What cells express MHC-II molecules?

    <p>Professional antigen presenting cells (pAPCs)</p> Signup and view all the answers

    What cells respond to MHC-II-restricted antigen presentation?

    <p>CD4 lymphocytes</p> Signup and view all the answers

    What is the purpose of MHC-I-restricted antigen presentation?

    <p>Select and activate CD8 lymphocytes</p> Signup and view all the answers

    What cells express MHC-I molecules?

    <p>Most somatic nucleated cells (APCs)</p> Signup and view all the answers

    What cells respond to MHC-I-restricted antigen presentation?

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

    What type of TCR is composed of one α-chain and one β-chain?

    <p>$α:β$ TCRs</p> Signup and view all the answers

    What type of TCR is made up of one γ-chain and one δ-chain?

    <p>$γ:δ$ TCRs</p> Signup and view all the answers

    What are the peptide binding domains of class I MHC molecules?

    <p>α1 and α2 domains of the heavy chain</p> Signup and view all the answers

    What are the peptide binding domains of class II MHC molecules?

    <p>α1 and α2 domains</p> Signup and view all the answers

    What is the length range of peptides that class II MHC molecules bind?

    <p>13 to 21 amino acids</p> Signup and view all the answers

    What is the length range of peptides that class I MHC molecules bind?

    <p>8 to 12 amino acids</p> Signup and view all the answers

    What is the main source of peptides for MHC-II molecules?

    <p>Endosomal compartments</p> Signup and view all the answers

    Which types of T lymphocytes do class I MHC molecules present antigenic peptides to?

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

    What is the function of HLA-DM proteins in the context of MHC class II molecules?

    <p>Catalyze the release of the clip peptide</p> Signup and view all the answers

    Where are acidified endocytic vesicles such as endosomes and phagolysosomes located?

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

    What is the role of the proteasome in the context of MHC class I molecules?

    <p>Generate antigenic peptides</p> Signup and view all the answers

    Which proteins are responsible for transporting peptides from the cytosol into the lumen of the endoplasmic reticulum?

    <p>TAP1 and TAP2</p> Signup and view all the answers

    What is the function of MHC class II molecules?

    <p>Present antigenic peptides to CD4+ T lymphocytes</p> Signup and view all the answers

    What is the role of cathepsins H, B, D, S and L in the context of MHC class II molecules?

    <p>Process peptides for antigen presentation</p> Signup and view all the answers

    What is the function of class I MHC molecules?

    <p>Present antigenic peptides to CD8+ T lymphocytes via their T cell receptor (TCR)</p> Signup and view all the answers

    What is the function of invariant chain (Ii) in the context of MHC class II molecules?

    <p>Prevent peptide loading inside the endoplasmic reticulum</p> Signup and view all the answers

    What is the maximum length of peptides that MHC-II molecules can bind?

    <p>21 amino acids</p> Signup and view all the answers

    Which proteins serve a peptide editing function in association with MHC class II molecules?

    <p>HLA-DM proteins</p> Signup and view all the answers

    Which molecule is required for the activation of Fyn by dephosphorylating it?

    <p>CD45</p> Signup and view all the answers

    How many peptide:MHC-II complexes are estimated to be sufficient to activate CD4 T lymphocytes?

    <p>10 to 50</p> Signup and view all the answers

    What is the function of the cytoplasmic domains of CD3 and the  homodimer?

    <p>Increase the efficiency of receptor signaling</p> Signup and view all the answers

    What is the role of ZAP-70 in T cell signaling?

    <p>It phosphorylates tyrosine residues in the ITAMs of CD3 and the  homodimer</p> Signup and view all the answers

    Which molecule is responsible for cleaving phosphatidylinositol biphosphate (PIP2) into diacylglycerol (DAG) and inositol triphosphate (IP3)?

    <p>PLC-</p> Signup and view all the answers

    What triggers complete activation of the T cell?

    <p>Peptide:MHC and CD28:CD80/86 interaction</p> Signup and view all the answers

    What drives the expression of IL-2 and high affinity IL-2 receptors?

    <p>CD28-mediated signaling</p> Signup and view all the answers

    Which of the following best describes the nomenclature used to define MHC I and MHC II alleles?

    <p>Alphanumeric combination based on chromosomal location</p> Signup and view all the answers

    What is responsible for the variability of peptides presented by MHC molecules?

    <p>Peptide cleavage specificity</p> Signup and view all the answers

    Which cells are involved in the antigen presentation via MHC class II molecules?

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

    What is the origin and source of the peptides presented by MHC class I molecules?

    <p>Endoplasmic reticulum and cytoplasm, self and foreign proteins</p> Signup and view all the answers

    Which proteins are mainly processed by the MHC class II-restricted antigen presentation machinery?

    <p>Extracellular bacterial proteins</p> Signup and view all the answers

    What is the process and outcome of MHC class II-restricted antigen presentation?

    <p>Phagocytosis and presentation to T helper cells, leading to immune activation</p> Signup and view all the answers

    Which type of cells interact in antigen cross-presentation involving non-classical MHC-I molecules?

    <p>Dendritic cells and B cells</p> Signup and view all the answers

    What is the significance of superantigen activation in antigen presentation mechanisms?

    <p>Leads to uncontrolled T cell activation and cytokine release</p> Signup and view all the answers

    What differs superantigens from antigens?

    <p>Superantigens bind directly to MHC molecules, bypassing normal antigen processing</p> Signup and view all the answers

    Which proteins form the CD3 signaling complex in the TCR?

    <p>CD3 δ-chain and CD3 γ-chain</p> Signup and view all the answers

    What delivers the survival signal to T lymphocytes in the form of surface co-stimulatory molecules CD80/86?

    <p>MHC class II molecules</p> Signup and view all the answers

    What is responsible for the variability of peptides presented by MHC molecules?

    <p>TAP proteins</p> Signup and view all the answers

    What is the function of HLA-DM proteins in the context of MHC class II molecules?

    <p>Peptide editing function</p> Signup and view all the answers

    What protein binds to the transmembrane tail of the TCR α:β heterodimer?

    <p>CD3 ζ homodimer</p> Signup and view all the answers

    What differs superantigens from antigens?

    <p>Superantigens have high specificity for TCR</p> Signup and view all the answers

    Which second messengers are involved in CD28-mediated signaling?

    <p>Phosphatidylinositide 3-kinase/Akt pathway and Ras-MAPK pathway</p> Signup and view all the answers

    What is the major outcome of CD28-dependent costimulation?

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

    Which cytokines are required for the differentiation of TH1 cells?

    <p>IL-12 &amp; IFN-</p> Signup and view all the answers

    What is the function of TH1 cells?

    <p>Control and/or elimination of intracellular microbes such as viruses and intracellular bacteria, fungi, and protozoans</p> Signup and view all the answers

    Which cells require a higher costimulatory threshold as compared to CD4+ T lymphocytes?

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

    What cytokines are required for the differentiation of TH2 cells?

    <p>TSLP (thymic stromal lymphopoietin), IL-25 &amp; IL-33</p> Signup and view all the answers

    What is the function of TH2 cells?

    <p>Involved in hypersensitivity reactions (e.g. asthma and allergic reactions)</p> Signup and view all the answers

    Which cytokines are required for the differentiation of TH17 cells?

    <p>IL-6 &amp; TGF-β</p> Signup and view all the answers

    What is the function of TH17 cells?

    <p>Secrete IL-17 &amp; Il-22</p> Signup and view all the answers

    What is the major outcome of cytotoxic T lymphocyte differentiation?

    <p>Expression of high levels of CD95L (CD178 or FasL), perforin, granzyme, granulolysin, as well as IFN- and other type I immunity cytokines</p> Signup and view all the answers

    Which cells generally require the help of TH1 cells for their activation?

    <p>Cytotoxic T cells (CTLs)</p> Signup and view all the answers

    What is the role of TH1 responses?

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

    What is the main purpose of TH17 responses?

    <p>Stimulating antimicrobial mediators at the site of infection</p> Signup and view all the answers

    What is the primary function of TH2 responses?

    <p>Driving class-switching towards IgE and IgG4</p> Signup and view all the answers

    What is the purpose of TFH cells?

    <p>Promoting B lymphocyte activation and germinal centre formation</p> Signup and view all the answers

    What is the main function of TREG cells?

    <p>Regulating immune responses and promoting peripheral tolerance</p> Signup and view all the answers

    Which cytokine is primarily associated with TH17 response?

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

    What is the key cytokine secreted by TFH cells?

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

    What is the main role of IL-22 in the immune response?

    <p>Increasing epithelial barrier functions and stimulating antimicrobial mediators at the site of infection</p> Signup and view all the answers

    What is the effect of IL-17 at the site of injury?

    <p>Promoting neutrophil recruitment and expression of antimicrobial mediators such as defensins</p> Signup and view all the answers

    What drives germinal centre formation and generation of high-affinity antibodies?

    <p>IL-21 secreted by TFH cells</p> Signup and view all the answers

    What is the primary reason for immune reactions to be inherently short-lived?

    <p>Continuous re-stimulation from antigens</p> Signup and view all the answers

    What enables the immune system to react rapidly to changes in the response?

    <p>Unstable mRNA of cytokines and cytokine receptors</p> Signup and view all the answers

    Which molecule has a much greater affinity for CD80/CD86 compared to CD28?

    <p>CTLA-4</p> Signup and view all the answers

    Under inflammatory conditions, what effect does increased CD80/CD86 avidity have?

    <p>Offsets CTLA-4 engagement</p> Signup and view all the answers

    What is the function of regulatory T lymphocytes (Treg) in relation to CD80/CD86 access to T lymphocytes?

    <p>Limit CD80/CD86 access</p> Signup and view all the answers

    Which inhibitory receptor is particularly important in therapeutics?

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

    What happens when a naïve T cell binds to peptide:MHC on a cell that does not express CD80/86?

    <p>Cell becomes anergic and cannot subsequently become activated</p> Signup and view all the answers

    What is the role of PD-L1 in relation to T cell activation termination?

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

    What is the outcome when Ag dwindles in the presence of CTLA-4 engagement?

    <p>Increased likelihood of CD28 engagement and immune response termination.</p> Signup and view all the answers

    What is the significance of engagement of PD-1 by PD-L1?

    <p>Terminates T cell activation.</p> Signup and view all the answers

    What is the primary function of CTLA-4 in relation to CD80/CD86 interaction?

    <p>Inhibits T cell activation.</p> Signup and view all the answers

    What is the estimated range of peptide:MHC-II complexes sufficient to activate CD4 T lymphocytes?

    <p>10 to 50 complexes</p> Signup and view all the answers

    Which protein is phosphorylated by Fyn, leading to the subsequent phosphorylation of ZAP-70 in T cell signaling?

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

    What is the primary function of CD80 and/or CD86 on the surface of pAPCs in T cell activation?

    <p>Providing costimulatory signal</p> Signup and view all the answers

    What is the role of ZAP-70 in T cell signaling?

    <p>Phosphorylation of scaffold proteins LAT and SLP-76</p> Signup and view all the answers

    Which downstream signaling pathway results in the activation and nuclear translocation of the transcription factor AP-1?

    <p>MAPK pathway</p> Signup and view all the answers

    What triggers the expression of costimulatory molecules by pAPCs?

    <p>Innate immunity inflammation</p> Signup and view all the answers

    What is the primary function of phospholipase C-γ (PLC-γ) in T cell signaling?

    <p>Cleaving phosphatidylinositol biphosphate (PIP2) into DAG and IP3</p> Signup and view all the answers

    Which molecules trigger complete activation of T cells when interacting with CD28 on the T cell surface?

    <p>CD80 and/or CD86</p> Signup and view all the answers

    What is the estimated range of peptide:MHC-I complexes sufficient to activate CD8 T lymphocytes?

    <p>1 to 3 complexes</p> Signup and view all the answers

    What triggers the activation and nuclear translocation of the transcription factor nuclear factor kappa B (NF-κB) in T cell signaling?

    <p>DAG/PKC-θ pathway</p> Signup and view all the answers

    Which molecule is responsible for binding to the phosphorylated ITAMs of the ζ homodimer and subsequently phosphorylated by Lck in T cell signaling?

    <p>ZAP-70</p> Signup and view all the answers

    What is the role of phosphatidylinositol biphosphate (PIP2) cleavage in T cell signaling?

    <p>Producing DAG and IP3</p> Signup and view all the answers

    What is the estimated range of peptide:MHC-II complexes sufficient to activate CD4 T lymphocytes?

    <p>10 to 50 complexes</p> Signup and view all the answers

    How many peptide:MHC-I complexes are estimated to be sufficient to activate CD8 T lymphocytes?

    <p>1 to 3 complexes</p> Signup and view all the answers

    What is the role of the cytoplasmic domains of CD3 and the  homodimer in T cell receptor signaling?

    <p>Contain ITAMs for efficient receptor signaling</p> Signup and view all the answers

    What triggers the activation of Fyn in T cell signaling?

    <p>Clustering of TCR heterodimers with co-receptors and CD45</p> Signup and view all the answers

    Which protein binds (docks to) the phosphorylated ITAMs of the  homodimer in T cell signaling?

    <p>ZAP-70</p> Signup and view all the answers

    What is cleaved into diacylglycerol (DAG) and inositol triphosphate (IP3) in T cell signaling?

    <p>Phosphatidylinositol biphosphate (PIP2)</p> Signup and view all the answers

    What is activated as a result of PKC- activation by DAG in T cell signaling?

    <p>Nuclear factor kappa B (NF-B)</p> Signup and view all the answers

    What results from Ca2+/calcineurin signaling by IP3 in T cell signaling?

    <p>Nuclear factor of activated T cells (NF-AT)</p> Signup and view all the answers

    (NF-AT) undergoes nuclear translocation as a result of which signaling pathway in T cell signaling?

    <p>(Ca2+/calcineurin signaling by IP3)</p> Signup and view all the answers

    In which organ does the positive selection of thymocytes occur?

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

    What is the primary role of professional antigen presenting cells (pAPCs) in the context of T lymphocyte activation?

    <p>Antigen presentation to naïve T lymphocytes</p> Signup and view all the answers

    Which signaling molecules are required for the activation of cytotoxic T lymphocytes (CTLs) into becoming effector cells?

    <p>Co-stimulatory signals</p> Signup and view all the answers

    What is the purpose of MHC-II-restricted antigen presentation?

    <p>To activate CD4 T lymphocytes</p> Signup and view all the answers

    Where does the negative selection of thymocytes occur?

    <p>Bone marrow</p> Signup and view all the answers

    What is the main outcome of CD28-dependent costimulation in T cell activation?

    <p>Differentiation of naïve T cells into effector cells</p> Signup and view all the answers

    What is the main response if the pathogen is mainly found in vacuoles?

    <p>Secretion of IFN-γ by TH1 cells</p> Signup and view all the answers

    What is the outcome of IFN-γ released by TH1 cells if the infected cell is capable of microbicidal activity?

    <p>Activates the infected cell's microbicidal mechanisms</p> Signup and view all the answers

    Which type of cells primarily control vacuolar pathogens without the intervention of CTLs?

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

    What is the function of TH1 help for the activation of infected cells in response to vacuolar pathogens?

    <p>Release of IFN-γ by TH1 cells</p> Signup and view all the answers

    When TH1 cells provide CD40L and IFN-γ to macrophages, what is the outcome?

    <p>Enhanced lysosomal enzyme production in macrophages</p> Signup and view all the answers

    What cell type processes pathogen protein via MHC-II-restricted antigen presentation pathway to activate TH1 cells?

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

    Which type of pathogens reside primarily in host cell vacuolar compartments such as endosomes?

    <p>Intracellular bacteria</p> Signup and view all the answers

    What do noncytotoxic CD8 T lymphocytes do at the CTL/infected cell interface to control viruses?

    <p>Secretes IFN-γ to clear viruses from infected cells without killing them</p> Signup and view all the answers

    What does IFN-γ released by TH1 cells induce in cells capable of microbicidal activity?

    <p>Production of nitric oxide (NO) by infected cells</p> Signup and view all the answers

    What do TH1 cells primarily set aside for immunological memory?

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

    What is the main response if the pathogen is mainly found in the cytosol?

    <p>Activation of microbicidal activity in infected cells by CD8 T cells</p> Signup and view all the answers

    What is the main purpose of antigen presentation by macrophages in tissue?

    <p>To seek T cell help for further activation and enhanced microbicidal activity</p> Signup and view all the answers

    Which of the following best describes the function of CD8 T cells?

    <p>Release cytotoxins to kill infected cells</p> Signup and view all the answers

    What is required for effective CD8+ T lymphocyte activation in response to intracellular pathogens?

    <p>TH1 cell interaction with an pAPC</p> Signup and view all the answers

    What is the main outcome of cytotoxic T lymphocyte differentiation?

    <p>Killing of infected cells through apoptosis</p> Signup and view all the answers

    Why are intracellular pathogens better handled by a TH1 response that elicits predominantly a CTL response?

    <p>They require a higher threshold of CD86 costimulation</p> Signup and view all the answers

    What leads to the lymphocytosis observed in viral infections?

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

    Which proteins are used by cytotoxic T lymphocytes to kill infected cells?

    <p>Perforin, granulysin, and granzyme</p> Signup and view all the answers

    What enables clonally-expanded CTLs to search for and destroy infected cells in affected tissues?

    <p>Migration of memory CD8+ T cells from secondary lymphoid tissue</p> Signup and view all the answers

    What is responsible for the death of infected cells by apoptosis?

    <p>'Clean' death due to little release of DAMPs</p> Signup and view all the answers

    Which signaling molecules increase the efficiency of CTLs for effective response to intracellular pathogens?

    <p>IL-12, IL-18, and IFN-γ</p> Signup and view all the answers

    What is the function of TH1 responses in killing cells infected with cytosolic microorganisms?

    <p>Seeking T cell help for further activation and enhanced microbicidal activity</p> Signup and view all the answers

    What triggers the activation and nuclear translocation of NF-AT (nuclear factor of activated T-cells) in T cell signaling?

    <p>Phosphorylated ITAMs (immunoreceptor tyrosine-based activation motifs) on the ζ homodimer</p> Signup and view all the answers

    Which of the following is a primary mechanism involved in the pathophysiology of asthma and type I hypersensitivity?

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

    Which cytokines are primarily responsible for promoting B lymphocyte isotype-switching to IgE?

    <p>IL-4 and IL-13</p> Signup and view all the answers

    What is the main function of TREG cells?

    <p>Promote self-tolerance</p> Signup and view all the answers

    Which cells express high levels of PD-L1?

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

    What is the primary function of TH2 responses?

    <p>Control of large extracellular parasites</p> Signup and view all the answers

    How do CTLs kill infected/transformed cells?

    <p>By releasing perforin and granzymes</p> Signup and view all the answers

    What are TH17 cells useful for?

    <p>Inducing chemokine expression</p> Signup and view all the answers

    What cytokines do TFH cells secrete?

    <p>IL-21 and IL-6</p> Signup and view all the answers

    What ligands do TREG cells express?

    <p>CTLA-4 and PD-1</p> Signup and view all the answers

    Which chemokine receptor do B lymphocytes down-regulate and then increase expression of, in order to migrate towards the T cell zone?

    <p>CXCR5 and CCR7</p> Signup and view all the answers

    What drives germinal center formation and the generation of long-lived plasma cells?

    <p>CD40L and IL-21</p> Signup and view all the answers

    Which cytokines are involved in TH17 differentiation?

    <p>IL-6, TGF-β, IL-21, and IL-22</p> Signup and view all the answers

    What is the primary consequence of a missing MHC-I molecule?

    <p>Inadequate immune response to viruses</p> Signup and view all the answers

    What cytokines are secreted by TFH cells to drive appropriate isotype-switching for the pathogen and its localization?

    <p>IFN-γ, IL-4, IL-21</p> Signup and view all the answers

    What stimulates fibroblasts and epithelial cells to recruit newly formed neutrophils to the site of infection?

    <p>IL-17</p> Signup and view all the answers

    Where do extrafollicular T and B cells migrate back to, where the T cells become follicular helper T lymphocytes (TFH)?

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

    What is the primary function of high-affinity antibodies in the clearance of infection?

    <p>All of the above</p> Signup and view all the answers

    What is the primary role of TH17 cells in the immune response?

    <p>Recruiting neutrophils to the site of infection</p> Signup and view all the answers

    What cytokines are involved in driving isotype-switching appropriate for the pathogen and its localization by TFH cells?

    <p>IFN-γ, IL-4, IL-21</p> Signup and view all the answers

    What drives antibody production by B lymphocytes in the periphery as part of the TH17 response?

    <p>IL-17 and IL-22</p> Signup and view all the answers

    Which membrane-bound molecules on TFH cells drive germinal center formation and generation of long-lived plasma cells?

    <p>CD40L and ICOS</p> Signup and view all the answers

    What is the primary function of memory T cells?

    <p>To respond to specific antigen faster and better than naïve cells</p> Signup and view all the answers

    What is the outcome of the primary adaptive immune response in relation to memory T cells?

    <p>Memory T cells outnumber their naïve counterparts by several orders of magnitude</p> Signup and view all the answers

    What distinguishes memory T cells from primary naïve lymphocytes?

    <p>Memory T cells survive throughout the course of the primary immune response, while most effector cells are short-lived</p> Signup and view all the answers

    What is a characteristic of memory T lymphocytes in terms of abundance?

    <p>10 – 1000 fold more abundant than primary naïve lymphocytes</p> Signup and view all the answers

    What is the significance of memory T cells' capacity to respond to specific antigen faster and better than naïve cells?

    <p>It allows for faster and stronger immune response upon re-exposure to the same antigen</p> Signup and view all the answers

    What is a key characteristic of memory T lymphocytes in terms of survival?

    <p>Survive throughout the course of the primary immune response and proliferate after the infection is resolved</p> Signup and view all the answers

    Which cells inhibit the activation of their naïve counterparts upon subsequent infection?

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

    Which cells have already undergone isotype switching and somatic hypermutation?

    <p>Memory B cells</p> Signup and view all the answers

    Which marker is a characteristic of memory T cells?

    <p>CD45RO</p> Signup and view all the answers

    Which type of cells are the innate counterparts of TH1, TH2, and TH17 cells?

    <p>Innate lymphoid cells (ILCs)</p> Signup and view all the answers

    Which type of cells respond to MHC-I-like proteins and pathogen-derived ligands?

    <p>Natural Killer cells (NK cells)</p> Signup and view all the answers

    Which type of immune reaction primarily occurs in mucosa-associated lymphoid tissues (MALTs)?

    <p>Adaptive immune reactions</p> Signup and view all the answers

    Which cell type is involved in innate immune responses to large extracellular pathogens like worms?

    <p>ILC2s</p> Signup and view all the answers

    What is a main function of Natural Killer (NK) cells?

    <p>Respond to MHC-I-like proteins and pathogen-derived ligands</p> Signup and view all the answers

    What is the primary site of adaptive immune response for blood infections?

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

    Which development relies on CD4 T lymphocyte help and IL-2 stimulation?

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

    Which type of immune responses do ILC3s and TH17 lymphocytes respond to?

    <p>Microscopic extracellular pathogens like bacteria and fungi</p> Signup and view all the answers

    What is a main function of ILC1s?

    <p>Secrete IFN-γ during innate immune responses to intracellular pathogens like viruses</p> Signup and view all the answers

    How many MHC-I genes are there in humans?

    <p>3</p> Signup and view all the answers

    How many MHC-II genes are there in humans?

    <p>3</p> Signup and view all the answers

    What does it mean for MHC expression to be co-dominant?

    <p>Both alleles of a gene are expressed equally</p> Signup and view all the answers

    What is the genetic make-up-based method to calculate the number of MHC-I types a person possesses?

    <p>Counting the number of HLA-A, HLA-B, and HLA-C alleles</p> Signup and view all the answers

    How polymorphic are MHC genes?

    <p>Highly polymorphic with hundreds of alleles per gene</p> Signup and view all the answers

    How many MHC-I types can be expressed on cells in theory?

    <p>Minimum of 6 and maximum of 18</p> Signup and view all the answers

    What is the average number of MHC-I types expressed on cells?

    <p>8</p> Signup and view all the answers

    How many MHC-II types can be expressed on cells in theory?

    <p>Minimum of 3 and maximum of 12</p> Signup and view all the answers

    What is the average number of MHC-II types expressed on cells?

    <p>8</p> Signup and view all the answers

    What is the location of human MHC genes?

    <p>Chromosome 6</p> Signup and view all the answers

    What do HLA genes encode for?

    <p>Both the α and β chains of class I MHC molecules</p> Signup and view all the answers

    Which molecule is recognized by NKG2D homodimers on the surface of NK cells, signaling the NK cell to kill the cell it has docked to?

    <p>MICA or MICB</p> Signup and view all the answers

    What is the primary function of NK cells in the context of antibody-dependent cell cytotoxicity (ADCC)?

    <p>Participating in antibody-mediated cell cytotoxicity</p> Signup and view all the answers

    Which type of cells primarily control vacuolar pathogens without the intervention of CTLs?

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

    What is the function of natural killer T cells (NKT cells) in response to glycolipid antigen presentation by MHC-I-like molecules?

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

    What is the main outcome of CD28-dependent costimulation in T cell activation?

    <p>Expression of IL-2 and high affinity IL-2 receptors</p> Signup and view all the answers

    What is the primary role of professional antigen presenting cells (pAPCs) in the context of T lymphocyte activation?

    <p>Antigen presentation via MHC class II molecules</p> Signup and view all the answers

    What drives germinal center formation and the generation of long-lived plasma cells?

    <p>Antibody production by B lymphocytes in the periphery as part of the TH17 response</p> Signup and view all the answers

    Which proteins form the CD3 signaling complex in the TCR?

    <p>Expression of IL-2 and high affinity IL-2 receptors</p> Signup and view all the answers

    What is required in addition to MHC-restricted antigen presentation to achieve effector functions in T lymphocytes?

    <p>CD28-dependent costimulation</p> Signup and view all the answers

    What protein binds to the transmembrane chaperone protein calnexin and the enzyme ERp57?

    <p>Role of phospholipase C-γ (PLC-γ) in T cell signaling</p> Signup and view all the answers

    What differs superantigens from antigens?

    <p>Function of regulatory T lymphocytes (Treg) in relation to CD80/CD86 access to T lymphocytes</p> Signup and view all the answers

    What is the primary difference between Type a IELs and CTLs?

    <p>Type a IELs interact with non-classical MHC-I molecules, while CTLs interact with classical peptide:MHC-I ligands.</p> Signup and view all the answers

    What is the role of NKG2D homodimers in Type a IELs and Type b IELs?

    <p>Activate killing by binding to non-classical MHC-I molecules</p> Signup and view all the answers

    What is the unconventional co-receptor possessed by Type b IELs?

    <p>Unconventional α:αCD8 homodimer co-receptor</p> Signup and view all the answers

    What is the function of superantigens in T cell activation?

    <p>Non-specific activation of CD4+ lymphocytes</p> Signup and view all the answers

    What is the consequence of superantigen activation of CD4+ lymphocytes?

    <p>Cytokine storm and immunosuppression</p> Signup and view all the answers

    Which downstream events are expected to be known as part of TCR signaling?

    <p>GTP/GDP-Ras MAPK &amp; SAPK/JNK, PLCγ signaling pathways</p> Signup and view all the answers

    Why is a high-affinity IL-2R (CD25) required for T lymphocyte activation?

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

    What happens if a T cell is presented antigen without co-stimulation?

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

    Why do CD8 T lymphocytes require CD4 T cell help for their activation?

    <p>To receive co-stimulatory signals from APCs via CD40L-CD40 interaction</p> Signup and view all the answers

    What is peripheral tolerance in the context of T lymphocytes?

    <p>Mechanisms that prevent self-reactive T cells from attacking normal host tissues</p> Signup and view all the answers

    What are the three signals required for T lymphocyte activation?

    <p>Antigen recognition, co-stimulation, cytokine signaling</p> Signup and view all the answers

    Which cells provide the activation signals required for T lymphocyte activation?

    <p>Macrophages and dendritic cells (DCs)</p> Signup and view all the answers

    Study Notes

    • Major histocompatibility complex (MHC) involves structures and functions of major histocompatibility complex molecules (MHC class I & II)
    • MHC class I & II: List genes, describe genetics, and nomenclature
    • MHC class I & II: Describe mechanisms for peptide variability, processing, presentation pathways
    • MHC class I: Antigen processing and presentation by cells like CD8 T lymphocytes, effects on infected or transformed cells
    • MHC class II: Antigen processing and presentation by cells like CD4 T lymphocytes, role in regulating immune responses
    • MHC-I & II: Discuss origin and source of peptides, antigen cross-presentation, superantigens, and non-classical MHC-I molecules
    • T lymphocyte biology: List and describe various cells, their functions, and migration
    • T lymphocytes: Recirculation, activation, proliferation, differentiation, cytokine involvement, TCR development, and signaling
    • CD4 & CD8 T cells: Differentiate TCRs, clonal expansion, effector functions, and regulation
    • Effector T cell populations: Contrast TH1, TH2, TH17, CTLs, TFH, and Treg, and their functions
    • Regulation and termination of adaptive immune responses: Describe importance of memory T cells.

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    Description

    Test your knowledge about the peptide binding domains in MHC class II molecules, and the variations in peptide lengths and anchor residue preferences. Learn about the differences in peptide presentation between MHC class I and class II.

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