MHC I and MHC II
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Questions and Answers

Which type of cells have MHC II molecules on their surface?

  • Effector T cells
  • All nucleated cells
  • Macrophages, dendritic cells, and B cells (correct)
  • Mature red blood cells

    • What is the function of MHC I molecules?

  • Present self and non-self pathogen antigens for initial T cell activation
  • Present self and non-self pathogen antigens to B cells for antibody production
  • All of the above
  • Present non-self pathogen antigens to effector T cells for cellular immunity (correct)

    • What is the composition of MHC I molecules?

  • One protein chain, α
  • One β protein chain and one γ2 microglobulin protein
  • One α protein chain and one β2 microglobulin protein (correct)
  • Two protein chains, α and β

    • What is the composition of MHC II molecules?

    <p>Two protein chains, α and β</p> Signup and view all the answers

    Where is the antigen-binding cleft located in MHC molecules?

    <p>Near the outermost portion of the dimer</p> Signup and view all the answers

    What is the function of MHC II molecules?

    <p>Present self and non-self pathogen antigens for initial T cell activation</p> Signup and view all the answers

    What is the role of dendritic cells in antigen presentation?

    <p>Recognize and attach to a pathogen cell</p> Signup and view all the answers

    What is the name of the process where antigen processing begins in a phagosome?

    <p>Phagolysosome formation</p> Signup and view all the answers

    What type of antigen epitopes are presented to T cells by MHC II?

    <p>Protein antigen epitopes</p> Signup and view all the answers

    What is the name of the mechanism by which epitopes are selected for processing and presentation by an APC?

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

    What happens to the most antigenic, immunodominant epitopes after they have been processed by an APC?

    <p>They associate within the antigen-binding cleft of MHC II molecules</p> Signup and view all the answers

    What is the name of the process where MHC I molecules present self and non-self pathogen antigens to effector T cells?

    <p>Cellular immunity</p> Signup and view all the answers

    Which cells have MHC II molecules on their surface?

    <p>Antigen-presenting cells</p> Signup and view all the answers

    What is the function of MHC I molecules in cellular immunity?

    <p>Present self and non-self pathogen antigens to effector T cells</p> Signup and view all the answers

    What is the composition of MHC I molecules?

    <p>A longer α protein chain and a smaller β2 microglobulin protein</p> Signup and view all the answers

    What is the composition of MHC II molecules?

    <p>Two protein chains, α and β</p> Signup and view all the answers

    What is the function of MHC II molecules in initial T cell activation?

    <p>Present non-self pathogen antigens for initial T cell activation</p> Signup and view all the answers

    What is the antigen-binding cleft for MHC I formed by?

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

    What is the antigen-binding cleft for MHC II formed by?

    <p>α1 and β1 domains</p> Signup and view all the answers

    What type of antigens are presented to T cells by MHC II?

    <p>Protein antigen epitopes</p> Signup and view all the answers

    Where are the most antigenic, immunodominant epitopes presented for T cell activation?

    <p>On the surface of antigen-presenting cells</p> Signup and view all the answers

    What is the function of lysosomes in antigen processing?

    <p>Contain antimicrobial enzymes and chemicals</p> Signup and view all the answers

    What cells recognize and attach to a pathogen cell for antigen processing?

    <p>Antigen-presenting cells</p> Signup and view all the answers

    What is the mechanism by which epitopes are selected for processing and presentation by an APC?

    <p>Complicated and not well understood</p> Signup and view all the answers

    Study Notes

    Major Histocompatibility Complex: MHC I and MHC II Molecules

    • Major Histocompatibility Complex (MHC) genes code for MHC molecules found on all nucleated cells of the body except mature red blood cells.
    • MHC I and MHC II molecules are involved in adaptive immunity.
    • MHC I molecules present self and non-self pathogen antigens to effector T cells for cellular immunity, whereas MHC II molecules present non-self pathogen antigens for initial T cell activation.
    • MHC I molecules are composed of a longer α protein chain and a smaller β2 microglobulin protein; only the α chain spans the cytoplasmic membrane. MHC II molecules are composed of two protein chains, α and β, which are approximately similar in length.
    • Both MHC I and MHC II molecules have a cleft that serves as the antigen-binding site near the outermost portion of the dimer.
    • The antigen-binding cleft for MHC I is formed by the α1 and α2 domains, whereas for MHC II, the cleft is formed by the α1 and β1 domains.
    • MHC II molecules are found only on the surface of antigen-presenting cells (APCs) such as macrophages, dendritic cells, and B cells.
    • After dendritic cells recognize and attach to a pathogen cell, the pathogen is internalized by phagocytosis and is initially contained within a phagosome.
    • Lysosomes containing antimicrobial enzymes and chemicals fuse with the phagosome to create a phagolysosome, where degradation of the pathogen for antigen processing begins.
    • Only protein antigen epitopes are presented to T cells by MHC II, and only a selection of the most antigenic or immunodominant epitopes are presented by APCs.
    • The mechanism by which epitopes are selected for processing and presentation by an APC is complicated and not well understood.
    • Once the most antigenic, immunodominant epitopes have been processed, they associate within the antigen-binding cleft of MHC II molecules and are translocated to the cell surface of the dendritic cell for presentation to T cells.

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    Description

    Test your knowledge of the Major Histocompatibility Complex (MHC) and its role in adaptive immunity with this quiz on MHC I and MHC II molecules. Learn about the composition and antigen-binding cleft of each molecule, the presentation of self and non-self pathogen antigens, and the antigen processing and presentation by antigen-presenting cells (APCs). Challenge yourself to understand the selection mechanism for epitopes and the translocation process for T cell presentation. Take this quiz and become an M

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