Immunology: Innate Immune Protection
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Questions and Answers

What is the primary function of the innate immune system?

  • To provide long-term immunity against specific pathogens
  • To prevent the entry of pathogens into the body (correct)
  • To produce antibodies in response to antigens
  • To activate T-lymphocytes to fight infections

    • What is a characteristic of the innate immune system?

  • It takes several days to respond to an infection
  • It responds differently to each infection
  • It is specific to each pathogen
  • It recognizes pathogens using a limited set of molecules (correct)

    • What is an example of a physical/anatomical barrier?

  • Cytokines
  • Natural antibodies
  • Phagocytes
  • Skin (correct)

    • Which of the following is NOT a component of the innate immune system?

    <p>B-lymphocytes</p> Signup and view all the answers

    How long does it take for the innate immune system to respond to an infection?

    <p>Several hours</p> Signup and view all the answers

    What is the relationship between the innate and adaptive immune systems?

    <p>The innate immune system induces and directs the adaptive immune response</p> Signup and view all the answers

    Which of the following is an example of a secreted compound?

    <p>Antibacterial compounds</p> Signup and view all the answers

    What is a characteristic of ancient evolution in the innate immune system?

    <p>It is found in invertebrates, such as amoebae and fruit flies</p> Signup and view all the answers

    What is the primary function of lysoszyme in tears, sweat, and saliva?

    <p>To destroy bacterial cell walls</p> Signup and view all the answers

    Which of the following is NOT a mechanical barrier protection mechanism?

    <p>Recognition of PAMPs</p> Signup and view all the answers

    What is the primary function of Toll-like receptors?

    <p>To recognize PAMPs</p> Signup and view all the answers

    What is the primary function of collectins?

    <p>To bind to sugar molecules on the surface of pathogens</p> Signup and view all the answers

    What is the time frame for the innate immune response?

    <p>0-4 hours</p> Signup and view all the answers

    What is the primary function of the innate immune response?

    <p>To recognize and eliminate pathogens</p> Signup and view all the answers

    What type of molecule is sensed by TLR4?

    <p>Lipopolysaccharide (LPS)</p> Signup and view all the answers

    Which NOD-like receptor senses muramyl dipeptide?

    <p>NOD2</p> Signup and view all the answers

    What is the primary function of the complement system?

    <p>Phagocytosis and killing</p> Signup and view all the answers

    Which of the following Toll-like receptors is involved in the recognition of RNA viruses?

    <p>TLR3</p> Signup and view all the answers

    What is the role of Toll-like receptors in the immune response?

    <p>Recognition of pathogens</p> Signup and view all the answers

    Which molecule is sensed by NOD1?

    <p>g-glutamyl diaminopimelic acid</p> Signup and view all the answers

    What is the primary function of phagocytosis and killing in the immune response?

    <p>Elimination of pathogens</p> Signup and view all the answers

    Which of the following is NOT a component of the innate immune response?

    <p>Antibody production</p> Signup and view all the answers

    Which of the following is NOT a function of cytokines in the innate immune response?

    <p>Inhibiting phagocytosis</p> Signup and view all the answers

    What is the primary function of MBL in the MB-lectin pathway?

    <p>Recognizing mannose on pathogens</p> Signup and view all the answers

    Which of the following is a byproduct of the respiratory burst in neutrophils?

    <p>Reactive oxygen intermediates</p> Signup and view all the answers

    What is the primary function of C3 convertase in the classical pathway?

    <p>Cleaving C3 into C3a and C3b</p> Signup and view all the answers

    Which of the following is NOT a function of phagocytosis?

    <p>Production of cytokines</p> Signup and view all the answers

    What is the primary function of iNOS in macrophages?

    <p>Producing nitric oxide radicals</p> Signup and view all the answers

    Which of the following is a function of chemokines?

    <p>Enabling cell migration to infected tissue</p> Signup and view all the answers

    What is the primary function of C1q in the classical pathway?

    <p>Recognizing antibody complexes</p> Signup and view all the answers

    Which of the following is NOT a type of immune response?

    <p>Synthetic immune response</p> Signup and view all the answers

    What is the primary function of the skin in the innate immune response?

    <p>Preventing pathogen entry</p> Signup and view all the answers

    What type of cells produce IL-8?

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

    What is the primary function of Natural Killer Cells?

    <p>To kill virally infected cells and tumour cells</p> Signup and view all the answers

    What is the role of IL-12 in the immune response?

    <p>To activate macrophages</p> Signup and view all the answers

    What is the role of MHC molecules in antigen presentation?

    <p>To present antigen to T cells</p> Signup and view all the answers

    What is the primary function of Dendritic Cells?

    <p>To present antigen to T cells</p> Signup and view all the answers

    What is the role of C3a, C3, and C3b in the immune response?

    <p>To opsonise pathogens for phagocytosis</p> Signup and view all the answers

    What is the primary mechanism of action of type 1 interferons?

    <p>To respond to virally infected cells</p> Signup and view all the answers

    What is the primary function of the innate immune response?

    <p>To recognize and eliminate pathogens</p> Signup and view all the answers

    Study Notes

    Innate Immunity

    • Innate immunity is a non-specific defense mechanism that responds immediately or within hours of exposure to an antigen.
    • It is the immunity you are born with, designed to be fast, and responds in the same way each time.
    • Innate immunity uses a handful of molecules to recognize infection and induces and directs the acquired/adaptive immune response.

    Components of Innate Immunity

    • Physical/anatomical barriers:
      • Skin
      • GI tract
      • Respiratory tract
      • Mucosal epithelia
    • Secreted compounds:
      • Antibacterial compounds
      • Complement
      • Natural antibodies
      • Cytokines
    • Cellular components:
      • Phagocytes
      • NK cells

    Goals of Innate Immune Response

    • Prevent entry of pathogens
    • Recognize the pathogen
    • Eliminate the pathogen

    Physical Barrier Protection

    • Skin: prevents entry of pathogens
    • GI tract: peristalsis, hydrochloric acid production, low pH
    • Eyes: blinking, tears containing lysopzyme that destroys bacterial walls

    Immune Protection

    • Preventing pathogen entry:
      • Physical
      • Mechanical
      • Secreted
    • Recognizing the pathogen:
      • Pattern recognition receptors (PRRs)
      • Collectins (bind to sugar molecules on the pathogen's surface)
      • Toll-like receptors (TLRs)
      • Nod-like receptors (NLRs)

    Pattern Recognition Receptors (PRRs)

    • Recognize pathogen-associated molecular patterns (PAMPs)
    • Examples of PAMPs:
      • Lipopolysaccharide (LPS) from Gram-negative bacteria
      • Lipoteichoic acid from Gram-positive bacteria

    Toll-Like Receptors (TLRs)

    • At least 10 mammalian homologues
    • Recognize PAMPs from various microorganisms
    • Examples:
      • TLR4 recognizes LPS from Gram-negative bacteria
      • TLR2 recognizes peptidoglycan from Gram-positive bacteria

    Effector Mechanisms of Innate Immune Response

    • Complement
    • Phagocytosis and killing
    • Cytokines
    • Activation of adaptive immunity

    Complement

    • Series of proteins that circulate in blood and tissue fluids
    • Operates via a cascade
    • Key protein: C3, which is activated by C3 convertase

    Phagocytosis

    • Recognition of the pathogen by receptors on the phagocyte leads to ingestion and destruction
    • Types of phagocytes:
      • Monocyte/macrophage
      • Neutrophil

    Killing Mechanisms

    • Reactive oxygen intermediates (more in neutrophils)
    • Reactive nitrogen intermediates (more in macrophages)

    Cytokines

    • Proteins that act as intercellular messengers
    • Bind to specific receptors
    • Can be activating or deactivating
    • Examples:
      • IL-1 (interleukin 1)
      • IL-6 (interleukin 6)
      • TNFa (tumor necrosis factor alpha)

    Chemokines

    • Class of cytokines with chemoattractant properties
    • Promote inflammation by enabling cells to adhere to the surface of blood vessels and migrate to infected tissue

    Interferons

    • Type 1 interferons (IFNa and IFNb) produced in response to virally infected cells
    • Natural Killer Cells:
      • Kill virally infected cells and tumor cells
      • Responsive to TNFa, IL-12
      • Produce IFNg

    Innate Immunity to Adaptive Immune Response

    • Antigen presenting cell (APC) recognizes the pathogen and presents the antigen to T cells
    • Signal 1: TCR recognizes the antigen
    • Signal 2: co-stimulation (CD28, CD86)
    • Cytokines (IL-12, IL-6, TNFα) stimulate the activation of T cells

    Antigen Presenting Cells

    • Macrophage
    • B cell
    • Dendritic cell

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    Description

    This quiz covers the basics of innate immune protection, including epithelial barriers, phagocytes, and complement system. Learn about the first line of defense against microbes and how it works with adaptive immunity.

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