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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