Innate and Adaptive Immunity Overview
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Questions and Answers

Which of the following statements accurately describes the relationship between PAMPs and DAMPs?

  • PAMPs and DAMPs both activate the same set of pattern recognition receptors on immune cells.
  • PAMPs are recognized by the innate immune system, while DAMPs are recognized by the adaptive immune system.
  • PAMPs are derived from microbes and signal infection, while DAMPs are derived from damaged host cells and signal tissue injury. (correct)
  • Both PAMPs and DAMPs are exclusively produced by pathogens.

    • Which of the following is NOT a characteristic of a pathogen-associated molecular pattern (PAMP)?

  • PAMPs can distinguish between self and non-self.
  • PAMPs are encoded by genes that undergo somatic recombination. (correct)
  • PAMPs are often essential for the survival of the microbe.
  • PAMPs are recognized by pattern recognition receptors on immune cells.

    • Which of the following statements about alarmins is TRUE?

  • Alarmins activate the adaptive immune system, not the innate immune system.
  • Alarmins are a subset of DAMPs that are released from healthy cells during damage. (correct)
  • Alarmins are a subset of PAMPs that are specifically released by dying cells.
  • Alarmins are exclusively produced by pathogens.

    • Which of the following is NOT a common example of a PAMP?

    <p>Histone proteins (B)</p> Signup and view all the answers

    How are pattern recognition receptors (PRRs) involved in innate immunity?

    <p>PRRs bind to PAMPs and DAMPs, triggering signal transduction pathways that lead to antimicrobial and pro-inflammatory responses. (A)</p> Signup and view all the answers

    Which of the following statements about NOD-like receptors (NLRs) is FALSE?

    <p>NLRs are primarily found on the apical membrane of intestinal epithelial cells, ensuring they are exposed to microbial products in the gut lumen. (D)</p> Signup and view all the answers

    Which of the following is NOT a cell type known to express NOD-like receptors (NLRs)?

    <p>T lymphocytes (B)</p> Signup and view all the answers

    Which of the following functions is NOT associated with NOD-like receptors (NLRs)?

    <p>Activation of adaptive immune responses (D)</p> Signup and view all the answers

    What is the primary location of NOD-like receptors (NLRs) within the cell?

    <p>Cytoplasm (D)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of NOD-like receptors (NLRs)?

    <p>They are exclusively triggered by pathogen-associated molecular patterns (PAMPs). (C)</p> Signup and view all the answers

    Which of the following best describes the role of NLRs in innate immunity?

    <p>NLRs play a crucial role in detecting both microbial and non-microbial danger signals. (D)</p> Signup and view all the answers

    What is the main function of inflammasomes, which are induced by NOD-like receptors (NLRs)?

    <p>Initiate inflammatory responses and promote type I interferon production. (C)</p> Signup and view all the answers

    Which of the following statements accurately describes the relationship between NOD-like receptors (NLRs) and Toll-like receptors (TLRs)?

    <p>NLRs are intracellular receptors while TLRs are primarily located on the cell surface. (D)</p> Signup and view all the answers

    What is the primary function of the TIR domain within TLRs?

    <p>Initiating the signaling cascade by recruiting adaptor proteins. (D)</p> Signup and view all the answers

    Which of the following is NOT a direct consequence of TLR dimerization?

    <p>Direct degradation of the pathogen. (D)</p> Signup and view all the answers

    How do TLRs contribute to the enhancement of the respiratory burst?

    <p>Inducing the expression of genes encoding enzymes involved in the production of reactive oxygen species. (D)</p> Signup and view all the answers

    What is the primary function of the NOD domain in an NLR protein?

    <p>Self-oligomerization and formation of the inflammasome complex. (A)</p> Signup and view all the answers

    Which of these processes does NOT directly contribute to the degradation of engulfed pathogens within phagosomes?

    <p>TLR activation by pathogen-associated molecular patterns (PAMPs) (C)</p> Signup and view all the answers

    Which of the following is NOT directly involved in the activation of caspase-1?

    <p>LRR domain (A)</p> Signup and view all the answers

    What is the primary role of type I interferons (IFNα and IFNβ) in innate immunity?

    <p>Antiviral responses. (A)</p> Signup and view all the answers

    What is the role of the inflammasome complex in the activation of caspase-1?

    <p>The inflammasome complex provides a platform for pro-caspase-1 recruitment and activation. (C)</p> Signup and view all the answers

    How does the activation of caspase-1 lead to the production of active IL-1β and IL-18?

    <p>Caspase-1 cleaves the inactive precursors of IL-1β and IL-18, transforming them into active forms. (A)</p> Signup and view all the answers

    Which of these transcription factors is primarily responsible for the production of type I interferons?

    <p>IRF7 (C), IRF3 (D)</p> Signup and view all the answers

    What is the main function of gasdermin D in the inflammasome pathway?

    <p>Gasdermin D forms pores in the cell membrane, facilitating the release of active IL-1β and IL-18. (C)</p> Signup and view all the answers

    Which of the following is NOT activated by the TLR signaling pathway?

    <p>MAPK (D)</p> Signup and view all the answers

    How does IL-1β influence the activity of antigen-presenting cells (APCs)?

    <p>IL-1β promotes the expression of MHC molecules on APCs, enhancing their antigen presentation capabilities. (C)</p> Signup and view all the answers

    What is the primary role of the intracellular TIR domain in TLR signaling?

    <p>Recruiting adaptor proteins to initiate the signaling cascade. (D)</p> Signup and view all the answers

    Which of the following statements accurately describes the autocrine signaling property of IL-1β?

    <p>IL-1β affects both neighboring cells and the same cells that secreted it. (C)</p> Signup and view all the answers

    Which of the following is a consequence of TLR activation but NOT a direct consequence of ligand binding to the TLR?

    <p>Production of inflammatory cytokines (B)</p> Signup and view all the answers

    What is the main function of the LRR domain in NLR proteins?

    <p>Recognition of ligands. (D)</p> Signup and view all the answers

    What is the primary function of β-defensins in the context of the immune response?

    <p>Directly killing microbes and modulating the immune response. (B)</p> Signup and view all the answers

    Which of the following is NOT a typical consequence of inflammasome activation?

    <p>Activation of adaptive immune responses, such as the production of antibodies. (C)</p> Signup and view all the answers

    What is the key difference between pro-IL-1β and IL-1β?

    <p>Pro-IL-1β is a precursor of IL-1β, while IL-1β is the active form. (D)</p> Signup and view all the answers

    Study Notes

    Innate and Adaptive Immunity

    • Innate immunity recognizes broad classes of microbes using pathogen-associated molecular patterns (PAMPs).
    • Adaptive immunity is more specific, recognizing detailed microbial structures (antigens).
    • Innate immunity uses about 1000 different molecular patterns (estimated) to recognize different microbes.
    • Adaptive immunity is able to recognize over 10 antigens.
    • Innate immunity is germline encoded, with limited receptor diversity.
    • Adaptive immunity is encoded by gene segments through somatic recombination, leading to greater diversity.
    • Innate immunity can discriminate self from non-self through recognition of host cells' lack of PAMPs.
    • Adaptive immunity uses the process of eliminating or inactivating potentially harmful self-reactive lymphocytes to discriminate self from non-self.

    Microbial Substances

    • Microbial substances that stimulate innate immunity are commonly shared among different microbes.
    • These patterns are termed pathogen-associated molecular patterns (PAMPs).
    • PAMPs include viral nucleic acids, bacterial DNA, and LPS in gram-negative bacteria.
    • The innate immune system identifies these substances as foreign.

    Damage-Associated Molecular Patterns (DAMPs)

    • The innate immune system can also identify endogenous molecules liberated from damaged or dying cells.
    • These are called damage-associated molecular patterns (DAMPs).
    • DAMPs can be a result of injuries from infections, chemical toxins, trauma, or other causes.
    • DAMPs generally are not released from cells dying by apoptosis.

    Pattern Recognition Receptors

    • Cellular receptors for PAMPs and DAMPs are called pattern recognition receptors (PRRs).
    • PRRs are found on cell surfaces, within phagocytic vesicles, and within the cytosol.
    • Upon binding to PAMPs or DAMPs, PRRs initiate signal transduction pathways, triggering antimicrobial and proinflammatory functions within cells.

    Toll-like Receptors (TLRs)

    • Toll-like receptors (TLRs) are a critical class of PRRs, exhibiting evolutionary conservation.
    • They recognize various microbial products, and molecules expressed by stressed or damaged cells.
    • Humans have 10 different functional TLRs.
    • TLRs include an extracellular Leucine-rich repeat (LRR) domain and an intracellular Toll/Interleukin-1 receptor (TIR) domain, initiating signaling cascades.
    • TLR activation results in a series of signaling steps involving adaptor proteins and protein kinases, leading to the activation of various transcription factors (e.g., NF-κB, AP-1, IRF3, IRF7).
    • These factors stimulate the production of genes crucial for inflammatory responses, including cytokines, chemokines, and endothelial adhesion molecules; and type I interferons for viral defense.
    • TLR signaling initiates antimicrobial mechanisms like the respiratory burst, phagosome-lysosome fusion, and phagosome acidification.
    • TLRs promote the production of β-defensins for direct microbial killing and immune response modulation.

    Nod-like Receptors

    • In addition to TLRs, NOD-like receptors (NLRs) are cytosolic sensors of PAMPs and DAMPs.
    • They activate signal transduction pathways, promoting inflammation or type I IFN responses (antiviral).
    • NLRs assemble into inflammasomes to activate caspase-1.
    • Caspase-1 cleaves inactive precursors to form active pro-inflammatory cytokines IL-1β and IL-18.
    • These cytokines promote inflammation and tissue remodeling.

    Cytokines in Acute Inflammation

    • Cytokines like IL-1, TNF-α, IL-6, IL-8, and IL-12 coordinate the initial response to infection or tissue damage.
    • They can induce fever, increase vascular permeability, recruit immune cells, enhance antigen presentation, and promote various immune responses.

    Inflammatory Response

    • Inflammatory response involves changes to blood vessels to allow fluids and cells to reach the site of infection or injury.
    • Leukocytes (WBCs) are crucial and arrive via a multi-step process:
      • Thetering and rolling, slowing leukocyte movement to adhere to endothelium..
      • Firm adhesion, involving activation and binding of integrins.
      • Transmigration, involving squeezing through the endothelium.
      • Chemotaxis, guiding the leukocytes towards the injury site.

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    Description

    This quiz explores the fundamental differences between innate and adaptive immunity. It covers aspects such as recognition mechanisms, receptor diversity, and the specific functions of each immune response. Test your knowledge on how these two systems work together to protect the body.

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