Adaptive Immunity and MHC Complexes
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Questions and Answers

What is a critical outcome of the site-specific recombination process?

  • All DNA between the joined segments is lost. (correct)
  • Only the variable regions are lost.
  • All DNA segments are preserved.
  • Episomes are retained in the nucleus.

    • What structural classification does the BCR fall under?

  • Heterotetramer (correct)
  • Homotetramer
  • Dimer
  • Monomer

    • In which phase of the cell cycle does V-D-J recombination occur?

  • Throughout the M phase
  • In the G0-G1 phase (correct)
  • In the G2 phase
  • During the S phase

    • Which components are involved in the initial step of the V-D-J recombination process?

    <p>D and J segments</p> Signup and view all the answers

    Which components make up the co-receptor for the BCR?

    <p>Igα and Igβ</p> Signup and view all the answers

    What is the role of alternative splicing in the maturation of RNA?

    <p>It brings the V-D-J segments close to the constant portion.</p> Signup and view all the answers

    How are the heavy and light chains of the BCR synthesized?

    <p>Independently from different genes</p> Signup and view all the answers

    What characterizes the timing of V-D-J recombination?

    <p>It is regulated to occur in immature T and B cells.</p> Signup and view all the answers

    What role does the ITAM domain play in the BCR signaling process?

    <p>It initiates signal transduction when the BCR binds an antigen</p> Signup and view all the answers

    What structure is formed from the DNA that is removed during site-specific recombination?

    <p>It is degraded as an episome.</p> Signup and view all the answers

    What occurs during the maturation of T and B cells?

    <p>Receptors are expressed without any prior antigen exposure</p> Signup and view all the answers

    What best describes the V-D-J recombination process?

    <p>It is tissue-specific, occurring only in B and T cells.</p> Signup and view all the answers

    What is the main component of the BCR responsible for binding to specific antigens?

    <p>Extracellular portion</p> Signup and view all the answers

    During the process of V-D-J recombination, how are the segments brought close to each other?

    <p>By the action of specific proteins.</p> Signup and view all the answers

    Which statement is true regarding the surface receptor expression in T and B cells?

    <p>Receptors appear prior to antigen exposure</p> Signup and view all the answers

    What is the significance of the BCR being unable to transduce signals independently?

    <p>It maintains signaling specificity</p> Signup and view all the answers

    What is the role of sphingosine I phosphate (S1P) receptors in T lymphocytes?

    <p>Regulate lymphocyte exit from lymphoid tissue.</p> Signup and view all the answers

    How does the presence of interferon type I (IFN I) affect T lymphocyte S1P receptors?

    <p>It inhibits the expression of S1P receptors after lymphocyte activation.</p> Signup and view all the answers

    What happens to naive T lymphocytes when they enter the lymph nodes?

    <p>They internalize their S1P receptors.</p> Signup and view all the answers

    What occurs when T cells encounter a specific antigen in the lymph nodes?

    <p>They reduce their ability to exit the lymph nodes.</p> Signup and view all the answers

    What is the fate of activated T cells after they fully differentiate?

    <p>They express S1P receptors and migrate out of lymph nodes.</p> Signup and view all the answers

    How frequently do lymphocytes check secondary lymphoid organs for antigens?

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

    What is the consequence of a T cell not recognizing any antigen within the lymph nodes?

    <p>It will remain in the lymph nodes without activation.</p> Signup and view all the answers

    What is the primary function of sphingosine as a lipid in the lymphatic system?

    <p>To serve as a chemoattractant factor for lymphocytes.</p> Signup and view all the answers

    What does V-D-J recombination achieve in the process of T cell receptor formation?

    <p>It randomly selects one segment from each variable, diversity, and joining region.</p> Signup and view all the answers

    In contrast to the β chain, how does the δ chain differ in its variable region segments?

    <p>The δ chain has fewer segments than the β chain.</p> Signup and view all the answers

    Which statement about the diversity of T cell receptors is true?

    <p>The diversity in receptors is limited by the number of DNA segments available.</p> Signup and view all the answers

    Which regions must be combined to create a functional exon for the β chain?

    <p>A segment from the variable, diversity, and joining regions.</p> Signup and view all the answers

    What role do stromal and epithelial thymic cells play in T cell receptor development?

    <p>They influence the opening of chromatin in specific regions.</p> Signup and view all the answers

    Why might the γ-δ receptor have less diversity compared to the α-β receptor?

    <p>It has fewer available DNA segments for recombination.</p> Signup and view all the answers

    What structural feature distinguishes the α chain from the δ chain?

    <p>The α chain has a greater variety of segments in its joining region.</p> Signup and view all the answers

    How many different types of segments make up the diversity region of the β chain?

    <p>2 segments</p> Signup and view all the answers

    What is the origin of B1 cells during development?

    <p>Fetal liver hematopoietic stem cells</p> Signup and view all the answers

    Which surface immunoglobulin is associated with follicular B cells?

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

    What is the function of the chemokine receptor CCR7 in naive lymphocytes?

    <p>Guides naive lymphocyte recirculation</p> Signup and view all the answers

    Which statement is true regarding B1 cells after birth?

    <p>Their levels decline after the first day of life</p> Signup and view all the answers

    What role does L-Selectin play in lymphocyte recirculation?

    <p>Adhesion to endothelial cells</p> Signup and view all the answers

    Which of the following describes the function of sphingosine 1-phosphate receptor in T cells?

    <p>Mediates exit from lymphoid organs</p> Signup and view all the answers

    What type of cells are formed in secondary lymphoid organs from immature B cells?

    <p>Follicular B cells or marginal zone B cells</p> Signup and view all the answers

    What is commonly true about the immunoglobulins expressed on the surface of B cells?

    <p>They express either IgG or IgM</p> Signup and view all the answers

    What is the primary function of TCR receptors on T lymphocytes?

    <p>To interact with the HLA complex along with peptides</p> Signup and view all the answers

    Which types of receptors are NOT found on B cells?

    <p>TCR receptors</p> Signup and view all the answers

    Which cellular component is NOT essential for signaling transduction in T lymphocytes?

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

    What role do cytokine and chemokine receptors play in lymphocytes?

    <p>To help lymphocytes navigate to the site of infection</p> Signup and view all the answers

    Which of the following is a significant difference between T cells and B cells?

    <p>B cells bind antigens without the need for MHC presentation</p> Signup and view all the answers

    What is the function of adhesion molecules in T lymphocytes?

    <p>To facilitate interaction with antigen presenting cells</p> Signup and view all the answers

    What is the main purpose of the recombination of genes coding for antigen receptors in lymphocytes?

    <p>To allow binding to multiple pathogens</p> Signup and view all the answers

    Which of the following correctly describes CD4 and CD8 co-receptors on T lymphocytes?

    <p>They are involved in the interaction with the MHC complex</p> Signup and view all the answers

    Study Notes

    Adaptive Immunity

    • The innate immune system is the first line of defense against pathogens
    • It activates immediately upon pathogen entry
    • If pathogens are numerous, inflammation occurs, and the adaptive immune response is activated
    • The adaptive immune system comprises lymphocytes (T and B cells)
    • Lymphocytes have specific receptors (TCR and BCR) that identify unique pathogen-derived peptides presented on MHC complexes
    • Allows for a more potent response to pathogens compared to the innate system
    • This response is specific to the pathogen involved

    MHC Complexes

    • MHC complexes present peptides to circulating cells
    • Allow identification of intracellular pathogens
    • Two types of MHC complexes: class I and class II
    • Class I MHC presents intracellular peptides to cytotoxic T cells
    • Class II MHC presents extracellular peptides to helper T cells

    Pathogen Detection

    • Some pathogens can enter and replicate inside cells
    • The adaptive immune system has evolved to detect pathogens inside cells as well as those that remain outside cells
    • The MHC complex is crucial for this as it's how the adaptive immune system recognizes any pathogen
    • Peptides from the pathogen compete with peptides from normal endogenous proteins

    T Cell Activation

    • T cells have receptors (TCR) that bind peptides presented by MHC complexes
    • Activation occurs when a T cell's TCR recognizes a peptide and the cell becomes strictly connected
    • The activation of T cells initiates various effects, such as the release of perforin and/or granzyme
    • Cytokine release activates other cells that are involved in the adaptive immunity
    • The CD8 cells kill infected cells, differently from the CD4 cells which help in activating a humoral response

    Adaptive Immune Response Features

    • Recognition of specific peptides, enabling a tailored response to each pathogen
    • Clonal expansion of cells with the receptor: Only the cells that recognize the peptide expand and differentiate to form effector cells
    • Development of memory cells, providing long-term protection against reinfection. Memory cells are extremely important for vaccination strategies.

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    Adaptive Immune Cells PDF

    Description

    Test your understanding of adaptive immunity and the role of MHC complexes in pathogen detection. This quiz covers the basics of lymphocyte function, the types of MHC complexes, and their crucial roles in the immune response. Challenge yourself with questions that explore how the adaptive system responds to various pathogens.

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