Lec 2 Quiz
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Questions and Answers

Which of the following best describes the difference between pluripotent and multipotent cells?

  • Pluripotent cells can self-renew indefinitely, while multipotent cells have a limited capacity for self-renewal.
  • Multipotent cells are found only in adults, while pluripotent cells are only found in embryos.
  • Multipotent cells can only differentiate into cells of a specific tissue lineage, whereas pluripotent cells can differentiate into any cell from the three germ layers.
  • Pluripotent cells can differentiate into a wider range of cell types than multipotent cells. (correct)

    • During hematopoiesis, which of the following cell types is derived from the myeloid branch?

  • Treg
  • B-cell
  • Erythrocyte (correct)
  • NK cell

    • Which of the following is the correct sequence of events in phagocytosis?

  • Chemotaxis, membrane activation, adherence, phagosome formation, fusion, killing and digestion, release
  • Chemotaxis, adherence, membrane activation, phagosome formation, fusion, killing and digestion, release (correct)
  • Membrane activation, chemotaxis, adherence, phagosome formation, fusion, killing and digestion, release
  • Adherence, chemotaxis, membrane activation, phagosome formation, fusion, killing and digestion, release

    • What is the role of myeloperoxidase found in neutrophil granules?

    <p>Generating hypochlorous acid, a potent bactericidal oxidant. (C)</p> Signup and view all the answers

    How do neutrophils continue to function effectively even in the absence of oxygen within infected tissues?

    <p>They utilize abundant glycogen stores for glycolysis, enabling them to function under anaerobic conditions. (B)</p> Signup and view all the answers

    Which leukocyte is characterized by a multi-lobed nucleus (typically 2-5 lobes) connected by fine chromatin filaments and cytoplasm with neutrally staining specific granules?

    <p>Neutrophil (C)</p> Signup and view all the answers

    A patient's blood smear shows a high number of cells with kidney-shaped nuclei and lacy chromatin. Which type of leukocyte is most likely elevated?

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

    Which type of leukocyte is primarily responsible for killing antibody-coated parasites through the release of granule contents?

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

    A patient presents with symptoms of a severe allergic reaction. An elevated count of which type of leukocyte would be most indicative of this condition?

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

    How do NK cells differentiate between healthy and infected cells?

    <p>By recognizing the presence or absence of MHC Class I molecules. (D)</p> Signup and view all the answers

    Which leukocyte plays a critical role in bridging the innate and adaptive immune responses by activating T cells?

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

    What is the primary function of mast cells in the context of parasitic infections?

    <p>Releasing granules containing histamine and other active agents to expel parasites. (B)</p> Signup and view all the answers

    Which of the following correctly lists the leukocytes in order from most to least plentiful in the blood?

    <p>Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils (NLMEB) (A)</p> Signup and view all the answers

    Pathogen-associated molecular patterns (PAMPs) MUST have which of the following characteristics from the perspective of the host's immune system?

    <p>Conserved across a wide range of pathogens and distinguishable from self-patterns. (C)</p> Signup and view all the answers

    What is the immediate consequence of Pattern Recognition Receptor (PRR) activation on innate immune cells?

    <p>Activation of microbicidal activity and induction of pro-inflammatory responses. (C)</p> Signup and view all the answers

    Flashcards

    Multipotent

    Cells that can give rise to multiple cell types, but not all.

    Hematopoiesis

    Process of generating blood cells from stem cells.

    Phagocytosis

    The process where cells engulf and digest particles like bacteria.

    Neutrophil granules

    Granules in neutrophils contain substances for killing bacteria.

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    Neutrophil fate post-phagocytosis

    Neutrophils die after engulfing microorganisms and are cleared by macrophages.

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    Neutrophils

    White blood cells with 2-5 nuclear lobes, pink-grey cytoplasm, and abundant glycogen for glycolysis under anaerobic conditions.

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    Monocytes

    Large white blood cells that migrate into tissues and differentiate into macrophages.

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    Macrophages

    Large cells with a lightly stained, horseshoe-shaped nucleus, derived from monocytes.

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    Eosinophils

    White blood cells that kill antibody-coated parasites and are elevated in allergic reactions.

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    Basophils

    The least common granulocyte, involved in inflammatory reactions and containing histamine.

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    Natural Killer (NK) Cells

    Lymphocytes that kill virus-infected cells using granules containing perforin and granzymes.

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    Pathogen-associated Molecular Patterns (PAMPs)

    Conserved molecular patterns on pathogens recognized by the immune system.

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    Pattern Recognition Receptors (PRRs)

    Receptors that recognize PAMPs and activate immune responses.

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    White Blood Cell Count Ratio

    In uninfected blood, the ratio is 1 WBC to every 600-700 RBCs.

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    Infected vs. Healthy Cells

    Healthy cells express MHC class 1, preventing NK cells from releasing killing granules; infected cells lack MHC class 1.

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    Study Notes

    Multipotent and Pluripotent Cells

    • Multipotent cells can differentiate into multiple cell types.
    • Pluripotent cells can differentiate into all cell types in an adult organism.

    Hematopoiesis

    • Hematopoiesis is the generation of blood cells.
    • Myeloid lineage:
      • Granulocytes: neutrophils, eosinophils, basophils
      • Monocytes: macrophages, dendritic cells, mast cells
    • Lymphoid lineage:
      • Common T-cell/ILC precursor:
        • Common ILC precursor: NK cells, ILC1, ILC2, ILC3, LTi
        • Common T-cell precursor: CD8 T cells, common CD4 T-cell precursor
          • Treg cells, TH17 cells, TH2 cells, TH1 cells
      • B cells
    • Erythroid (megakaryocyte-erythroid precursor cell) lineage:
      • Erythroblast: erythrocytes
      • Megakaryocyte: platelets

    Phagocytosis

    • Phagocytosis is the cellular internalization of particulate matter (e.g., bacteria).
    • Process:
      • Chemotaxis
      • Adherence (PAMP recognition)
      • Membrane activation ("danger" signal)
      • Phagocytosis initiation
      • Phagosome formation
      • Fusion
      • Killing and digestion
      • Release of degradation products

    Neutrophil Fate After Phagocytosis

    • Neutrophils die in tissues and are engulfed/degraded by macrophages.

    Neutrophil Granules

    • Primary (azurophilic) granules:
      • Myeloperoxidase (creates "green" pus)
      • Hydrogen peroxide + chloride → hypochlorous acid (bactericidal)
      • Defensins, bactericidal permeability-increasing (BP) protein, cathepsin G
    • Secondary granules:
      • Lactoferrin
      • Lysozyme
      • Alkaline phosphatase
      • Membrane-bound cytochrome b558

    Characteristics of Immune Cells

    • Neutrophils: 2-5 nuclear lobes, pink/grey cytoplasm, abundant glycogen, multi-lobed nucleus
    • Macrophages: Large, lightly stained kidney-bean shaped nucleus, lacy chromatin, small dense granules.
    • Monocytes: Migrate to connective tissue, become macrophages.
    • Eosinophils: Kill antibody-coated parasites, abundant in intestinal mucosa and lungs, increased in parasitic infections, stimulated in allergic reactions by mast cells.
    • Basophils: Control immune responses to parasites, longest-lasting granulocyte (2 weeks), histamine, leukotrienes, heparin, involved in hypersensitivity and inflammatory reactions.
    • NK cells: Kill virus-infected cells, contain perforin, granzymes.
    • Dendritic cells: Activate T cells, initiate adaptive immune responses.
    • Mast cells: Expel parasites through histamine and other granule contents.

    Leukocyte Abundance (NLMEB)

    • Neutrophils: 48-78%
    • Lymphocytes: 20-40%
    • Monocytes: 2-8%
    • Eosinophils: 0-4%
    • Basophils: 0-1%

    WBC:RBC Ratio

    • 1 WBC to every 600-700 RBCs (uninfected state).

    NK Cell Function

    • Killing mechanism: Perforin forms pores in target cell membranes, granzymes enter, inducing apoptosis or osmotic lysis. α-defensins are also secreted.
    • Distinguishing normal from abnormal:
      • Healthy cells have MHC class I, activating an inhibitory receptor, preventing granule release.
      • Infected cells lack MHC class I, no inhibitory receptor activation, triggering granule release.

    PAMPs and PRRs

    • PAMPs (Pathogen-Associated Molecular Patterns): Pathogen molecules, conserved across many pathogens, easily distinguishable from host molecules.
    • PRRs (Pattern Recognition Receptors): Receptors on leukocytes that recognize PAMPs. Found in various cellular compartments and secreted forms. Multiple sub-families - TLRs, CLRs, NLRs, RLRs. Some are lectin-like, binding to microbial surface sugars.

    PAMP Ideal Characteristics (Pathogen Perspective vs. Our Perspective)

    • From the pathogen's perspective: conserved, shared by many pathogens, distinguishable from host patterns.

    PRR Activation Events

    • PRR activation elicits microbicidal and pro-inflammatory responses to eliminate pathogens.
    • Infection leads to PAMP recognition which activates PRRs
    • Injury causes DAMP (Damage-Associated Molecular Pattern) recognition.
    • Induces phagocytosis, cytokine secretion (which recruits immune cells), and adaptive immune cell co-stimulation.

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    Description

    Test your knowledge on multipotent and pluripotent cells, the intricacies of hematopoiesis, and the process of phagocytosis. Dive into the details of blood cell generation and internalization mechanisms. This quiz is designed for students focused on developmental biology and immunology.

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