Lecture 15
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Questions and Answers

What is the function of autophagosomes?

  • Create new proteins in the cytoplasm
  • Release cytoplasmic content into the extracellular space
  • Transport proteins to the Golgi apparatus
  • Contain cytoplasmic content and fuse with lysosomes (correct)
  • Under what conditions do autophagosomes form?

  • In the presence of a pathogen (correct)
  • After organelle repair
  • In nutrient-rich environments
  • In the absence of stress
  • What is the main mechanism of rejection of transplanted organs?

  • Direct recognition
  • Autophagy
  • MHC restriction
  • Allorecognition (correct)
  • What is the difference between direct and indirect allorecognition?

    <p>Direct targets donor MHC molecules, while indirect targets recipient APCs</p> Signup and view all the answers

    Which genes encode the alpha and beta chain of MHC Class II molecules?

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

    What does polymorphism refer to in terms of MHC genes?

    <p>Multiple variations or alleles existing for each gene</p> Signup and view all the answers

    Where are HLA genes located in humans?

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

    Which T cell recognition involves targeting regardless of the peptide presented?

    <p>Direct allorecognition</p> Signup and view all the answers

    What percentage of all T cells in an organism can react to non-self MHC molecules?

    <p>1-10%</p> Signup and view all the answers

    What characteristic does a locus represent?

    <p>Chromosomal location of a gene</p> Signup and view all the answers

    How many HLA-A alleles are there in the range of HLA-A1 to HLA-A2041?

    <p>2000 alleles</p> Signup and view all the answers

    What term describes the particular combination of MHC alleles found on a single chromosome?

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

    How many different MHC-I alleles can be expressed in an individual, considering inheritance from both parents?

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

    What feature of MHC genes makes human transplantation difficult?

    <p>Heterozygosity at each locus</p> Signup and view all the answers

    Where do most differences in MHC expression exist within the molecule?

    <p>Peptide Binding Groove</p> Signup and view all the answers

    Which term describes having multiple genes that encode for proteins with the same function?

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

    What process involves cytosolic peptides being presented on MHC Class II through autophagy?

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

    What is the unique ability of dendritic cells in the immune system?

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

    How are dendritic cells 'licensed' to perform cross-presentation of antigens?

    <p>By activating CD4+ T cells</p> Signup and view all the answers

    What is the role of a CD4+ T cell in the process of cross-presentation by dendritic cells?

    <p>Granting permission to dendritic cells for cross-presentation</p> Signup and view all the answers

    What is the significance of the 'license' granted by CD4+ T cells to dendritic cells?

    <p>It enables the redirection of exogenous antigens to MHC class I molecules</p> Signup and view all the answers

    Which type of T cell needs to be activated first for dendritic cells to license and cross-present antigens?

    <p>CD4+ T cell</p> Signup and view all the answers

    What happens after dendritic cells get permission from CD4+ T cells to redirect exogenous antigens?

    <p>They activate CD8+ T cells.</p> Signup and view all the answers

    Why is the redirection of exogenous antigens onto MHC class I molecules important?

    <p>To prime CD8+ cytotoxic T-cell responses</p> Signup and view all the answers

    What is the mechanism by which dendritic cells redirect exogenous antigens onto endogenous pathways?

    <p>By receiving permission signals from CD4+ T cells</p> Signup and view all the answers

    In the context of immune response, what is the role of cross-presentation by dendritic cells?

    <p>To activate cytotoxic immune responses against pathogens</p> Signup and view all the answers

    How does cross-presentation by dendritic cells contribute to immune surveillance?

    <p>By detecting and eliminating infected or abnormal cells</p> Signup and view all the answers

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