Innate Immunity and Inflammation 1
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Questions and Answers

What is the main function of cathelicidins?

  • To engulf and destroy microorganisms, especially bacteria
  • To recognize and destroy many pathogens without aid of an adaptive immune response
  • To kill microbes in response to inflammation (correct)
  • To act as a chemical barrier

    • Which of the following can trigger phagocytosis?

  • Binding to Pattern Recognition Receptors (PRRs)
  • Binding to a Lectin receptor
  • An antibody binds to an antigen (correct)
  • All of the above

    • Which cells are the major phagocytes in the body?

  • Defensins
  • Neutrophils (correct)
  • Lectins
  • Lysozymes

    • What type of cells are neutrophils?

    <p>Non-dividing, short-lived cells in blood</p> Signup and view all the answers

    What is the main mechanism for large molecules to move across the endothelium?

    <p>Pinocytosis (caveolin pathway)</p> Signup and view all the answers

    During inflammation, what contributes to the increased pressure in the interstitial space?

    <p>Increased production of interstitial fluid</p> Signup and view all the answers

    What occurs when lymphatic vessels themselves become inflamed?

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

    Which process involves the binding of selectins and rolling of cellular adhesion molecules to their respective ligands on leukocytes?

    <p>Both of the above</p> Signup and view all the answers

    Neutrophils, eosinophils, and basophils are examples of which type of cells that migrate from the circulation into inflamed tissue?

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

    Which type of receptor recognizes 'carbohydrate patterns' on bacterial, fungal, and parasitic cell walls?

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

    What is the main role of an opsonin in the process of phagocytosis?

    <p>To enhance the effectiveness of phagocytosis by coating the microbe</p> Signup and view all the answers

    Which receptor binds to complement opsonins found mostly on bacterial cell walls?

    <p>CR3</p> Signup and view all the answers

    What is the function of lectin receptors in the process of phagocytosis?

    <p>To recognize and bind to 'carbohydrate patterns' on microbial cell walls</p> Signup and view all the answers

    What is the role of PI3 kinase in the process of phagocytosis?

    <p>To mediate intracellular signaling events and actin polymerization</p> Signup and view all the answers

    Which type of receptor binds to the constant region of different antibody types?

    <p>Fc receptor</p> Signup and view all the answers

    In phagocytosis, what is the main function of a phagosome?

    <p>To engulf the microbe and form a compartment for degradation</p> Signup and view all the answers

    What is the primary role of calreticulin as a receptor in phagocytosis?

    <p>To bind to particular opsonins</p> Signup and view all the answers

    When a microbe binds to a PRR on a phagocyte, it can trigger phagocytosis and ______

    <p>cytokine secretion</p> Signup and view all the answers

    SRs (scavenger receptors) bind mostly to fungi and viruses

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

    Post phagocytosis of microbe, phagosome will dock with....

    <p>Lysosomes and/or neutrophil granules</p> Signup and view all the answers

    Phagosomes are able to kill microbes engulfed through their....

    <p>All of the above</p> Signup and view all the answers

    What role does NADPH oxidase complex play in phagocytosis?

    <p>Creates oxygen species that can kill microbes</p> Signup and view all the answers

    When do NETs occur?

    <p>When neutrophils are surrounded by many bacteria</p> Signup and view all the answers

    When an environment is filled with many bacteria, neutrophils lyse and release their ______ into the ECF to trap the bacteria

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

    The fusion of a superoxide with nitric oxide forms_______, which is a nitric oxide super radical that can even damage our own cells

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

    Lactoferrin is found in neutrophil granules and can impede _______ metabolism, which is essential for bacterial metabolism

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

    Defensins, Cathepsins, Cathelicidins and lysozymes are all found in....

    <p>Neutrophil granules</p> Signup and view all the answers

    Which of the following roles do cytokines play in an immune response?

    <p>All of the above</p> Signup and view all the answers

    Interferons are mostly released in the presence of....

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

    Patients with Myd88 deficiency suffer from....

    <p>More frequent and severe bacterial infections</p> Signup and view all the answers

    What is the consequence of Myd88 binding to TLRs on phagocytes?

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

    TLRs have variable specificity for a range of pathogens

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

    Which of the following families of receptors are found intracellularly?

    <p>Nod-like receptors</p> Signup and view all the answers

    Toll-like receptors recognize products derived from the degradation of phagocytosed pathogens

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

    What is the main function of lipoxins in the inflammatory process?

    <p>Decrease inflammation</p> Signup and view all the answers

    Which enzyme generates arachidonic acid from membrane phospholipids?

    <p>PLA2</p> Signup and view all the answers

    What is the primary effect of important prostaglandins like PGE2, PGD2, and PGI2?

    <p>Vasodilation and increase in vascular permeability</p> Signup and view all the answers

    Which organ do leukotrienes play an important role in?

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

    What is the role of prostaglandin PGI2 in the inflammatory process?

    <p>Increase inflammation</p> Signup and view all the answers

    Which enzyme generates lipoxins from arachidonic acid?

    <p>12-lipoxygenase</p> Signup and view all the answers

    What is the main mechanism for large molecules to move across the endothelium?

    <p>Pinocytosis (caveolin pathway)</p> Signup and view all the answers

    During inflammation, what contributes to the increased pressure in the interstitial space?

    <p>Mechanisms of increased vascular permeability</p> Signup and view all the answers

    What occurs as interstitial fluid accumulates during inflammation?

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

    What are the major cells that migrate from the circulation into inflamed tissue?

    <p>Neutrophils, monocytes, eosinophils, and basophils</p> Signup and view all the answers

    What is the main function of a chemokine?

    <p>Induce movement of leukocytes along the chemokine concentration gradient</p> Signup and view all the answers

    What is the significance of the CXC chemokines?

    <p>Attract neutrophils to site of inflammation</p> Signup and view all the answers

    What is the first step in leukocyte migration?

    <p>Margination – leukocytes migrate towards vessel wall</p> Signup and view all the answers

    Which chemokine family primarily attracts neutrophils and has angiogenic properties?

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

    What is the role of chemokines in mediating adhesion of leukocytes?

    <p>Stimulate leukocytes to express integrin</p> Signup and view all the answers

    Which type of chemokine family acts on/attracts a wide variety of other leukocytes?

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

    What is the function of chemokines specifically in inflammation/migration?

    <p>Mediating adhesion</p> Signup and view all the answers

    Study Notes

    Cathelicidins and Phagocytosis

    • Cathelicidins function as antimicrobial peptides, playing a key role in innate immunity by disrupting microbial membranes.
    • Opsonins enhance phagocytosis by marking pathogens for engulfment.

    Phagocytes and Leukocytes

    • Major phagocytes in the body include macrophages and neutrophils.
    • Neutrophils are a type of white blood cell essential for immediate immune response.
    • Eosinophils and basophils, along with neutrophils, are leukocytes that migrate from circulation to inflamed tissues.

    Mechanisms of Endothelial Movement

    • Large molecules primarily cross the endothelium via transcytosis.
    • Increased interstitial fluid pressure during inflammation is caused by vascular leakage and accumulation of fluid.

    Inflammation and Lymphatics

    • Inflammation can lead to lymphatic vessel inflammation, resulting in impaired fluid drainage and increased swelling.
    • Binding of selectins and rolling adhesion of cells on leukocytes is involved in leukocyte trafficking during inflammation.

    Pattern Recognition and Opsonization

    • Pattern recognition receptors (PRRs) detect carbohydrate patterns on pathogens, facilitating immune response.
    • Opsonin receptors on phagocytes recognize complement proteins, especially on bacterial surfaces.

    Phagosome Functionality

    • Phagosomes engulf and kill microbes through fusion with lysosomes containing antimicrobial substances.
    • Calreticulin acts as a receptor that aids in opsonization and enhances phagocytic activity.

    Enzymatic Roles and Microbial Killing

    • The NADPH oxidase complex generates reactive oxygen species crucial for killing engulfed pathogens.
    • Neutrophils release neutrophil extracellular traps (NETs) when overwhelmed by bacteria to trap pathogens effectively.

    Nitric Oxide and Bacterial Metabolism

    • Fusion of superoxide with nitric oxide results in peroxynitrite, a potent reactive nitrogen species that can harm host tissues as well.
    • Lactoferrin, found in neutrophils, inhibits bacterial iron metabolism, essential for pathogen growth.

    Cytokines and Immune Response

    • Cytokines are signaling proteins that modulate immune responses, influencing inflammation and cell communication.
    • Interferons are often released in response to viral infections, enhancing the immune response.

    TLRs and Pathogen Recognition

    • TLRs (Toll-like receptors) recognize pathogen-associated molecular patterns (PAMPs) and initiate immune signals.
    • Myd88 plays a critical role in transducing signals from TLRs to enhance phagocytic actions.

    Lipid Mediators in Inflammation

    • Lipoxins are involved in the resolution phase of inflammation, helping to inhibit inflammatory responses.
    • Arachidonic acid is produced from membrane phospholipids by phospholipase A2, playing a key role in inflammatory pathways.

    Chemokines and Leukocyte Migration

    • Chemokines are essential for directing leukocyte migration during inflammation, signaling cells to reach the infection site.
    • CXC chemokines particularly attract neutrophils and can stimulate angiogenesis.
    • The first step in leukocyte migration involves their tethering and crawling along the endothelium in response to chemokine gradients.

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    Description

    Explore the roles and functions of defensins in the immune system, including their ability to kill microbes extracellularly and intracellularly. Learn about the process of phagocytosis and the role of phagocytes as a defense mechanism against invading microbes.

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