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Cytokines and Hematopoietic Stem Cells
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Cytokines and Hematopoietic Stem Cells

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Questions and Answers

What is the size range of a promyelocyte?

  • 10 to 15 μm
  • 31 to 40 μm
  • 26 to 30 μm
  • 16 to 25 μm (correct)

    • Primary granules are formed during the myelocyte stage.

    False

    What type of granules are produced first during neutrophil maturation?

    Primary granules

    The _______ is the final stage in which cell division occurs.

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

    Match the type of granule with its characteristic:

    <p>Primary granules = Formed during promyelocyte stage Secondary granules = Identifies cells as neutrophilic Tertiary granules = Formed during metamyelocyte and band stages Secretory granules = First to be released during neutrophil stages</p> Signup and view all the answers

    Which of the following features is not associated with myeloblasts?

    <p>Presence of primary granules</p> Signup and view all the answers

    Promyelocytes account for 1% to 5% of the nucleated cells in the bone marrow.

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

    What is the N:C ratio for a promyelocyte?

    <p>3:1</p> Signup and view all the answers

    Which cytokine is primarily responsible for stimulating neutrophil production?

    <p>Granulocyte colony-stimulating factor (G-CSF)</p> Signup and view all the answers

    What is a key cytoplasmic feature of late myelocytes?

    <p>Their cytoplasm is more lavender-pink than blue.</p> Signup and view all the answers

    Hematopoietic stem cells (HSCs) can be recognized with a light microscope.

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

    The nucleus of a metamyelocyte typically has prominent nucleoli.

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

    What is the role of cytokines in relation to stem cells?

    <p>Cytokines modulate the functional activities of stem cells, influencing their production, differentiation, and trafficking.</p> Signup and view all the answers

    What happens to the primary granules in late myelocytes?

    <p>They decrease in number and become less visible.</p> Signup and view all the answers

    The type of cell that is the earliest in the neutrophil development process is called a __________.

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

    Match the following terms with their corresponding definitions:

    <p>Hematopoietic stem cells (HSCs) = Cells capable of self-renewal and differentiation Cytokines = Soluble proteins that modulate cell functions Granulocyte colony-stimulating factor (G-CSF) = Stimulates neutrophil production Colony-stimulating factors (CSFs) = Promote the production of blood cells</p> Signup and view all the answers

    Late myelocytes are somewhat smaller than promyelocytes, measuring between _____ μm.

    <p>15 to 18</p> Signup and view all the answers

    Which of the following is NOT a type of cytokine?

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

    Match the following cell types with their characteristic features:

    <p>Early Myelocyte = Patches of grainy pink cytoplasm present Late Myelocyte = More lavender-pink cytoplasm Metamyelocyte = Indented nucleus with increasing chromatin clumping Promyelocyte = Contains mostly primary granules</p> Signup and view all the answers

    What percentage of nucleated cells in the bone marrow do myelocytes typically represent?

    <p>6% to 17%</p> Signup and view all the answers

    Colony-stimulating factors (CSFs) are low in specificity and inactive at low concentrations.

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

    Name one characteristic feature of myeloblasts.

    <p>Myeloblasts have a high nucleus-to-cytoplasm (N:C) ratio and may contain 0 to more than 20 granules.</p> Signup and view all the answers

    Tertiary granules begin to synthesize during the myelocyte stage.

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

    What distinguishes early myelocytes from promyelocytes?

    <p>The presence of secondary granules in the cytoplasm.</p> Signup and view all the answers

    What is the approximate daily production of neutrophils per kg of body weight?

    <p>0.9 × 10^9 cells/kg</p> Signup and view all the answers

    Band neutrophils have an indentation less than half the width of the nucleus.

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

    What stimulates the release of granulocytes from the bone marrow?

    <p>G-CSF</p> Signup and view all the answers

    The half-life of neutrophils in the blood is approximately ___ hours.

    <p>7</p> Signup and view all the answers

    Which neutrophil pool is localized to the walls of capillaries in tissues like the liver and lung?

    <p>Marginated neutrophil pool</p> Signup and view all the answers

    The maturation pool in the bone marrow contains roughly ___ cells/kg.

    <p>5.6 × 10^9</p> Signup and view all the answers

    The maturation pool in the bone marrow is capable of cell division.

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

    Match the following neutrophil pools with their characteristics:

    <p>Proliferative pool = Capable of division Maturation pool = Not capable of division Circulating neutrophil pool = Active in blood Marginated neutrophil pool = Localized to capillary walls</p> Signup and view all the answers

    What is the primary function of neutrophils?

    <p>Phagocytosis and destruction of foreign material</p> Signup and view all the answers

    Neutrophils provide specific protection against reexposure to the same pathogen.

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

    What are the two main processes involved in the seeking action of neutrophils?

    <p>Chemotaxis and motility</p> Signup and view all the answers

    Neutrophils undergo _____ when they escape the interior of the blood vessel through the endothelium.

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

    Match the following neutrophil functions with their descriptions:

    <p>Chemotaxis = Movement towards chemical signals Phagocytosis = Engulfing and digesting foreign material Diapedesis = Transmigration through the endothelium NETs = Extracellular traps formed by DNA</p> Signup and view all the answers

    What role do CD18 integrins play in neutrophil function?

    <p>Facilitating firm adhesion to endothelial cells</p> Signup and view all the answers

    Chemotactic agents are produced exclusively by microorganisms.

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

    What structure do neutrophil extracellular traps (NETs) represent?

    <p>Chains of nucleosomes from unfolded nuclear chromatin material (DNA)</p> Signup and view all the answers

    Study Notes

    Hematopoietic Stem Cells (HSCs)

    • HSCs are capable of self-renewal and differentiation into various blood cell types.
    • Cannot be distinguished using light microscopy and Romanowsky staining.

    Cytokines and Growth Factors

    • A diverse group of soluble proteins that modulate cell activities, often referred to interchangeably as growth factors.
    • Most cytokines are glycoproteins responsible for stimulation or inhibition of blood cell production, differentiation, or trafficking.

    Types of Cytokines

    • Interleukins (ILs)
    • Lymphokines
    • Monokines
    • Interferons
    • Chemokines
    • Colony-stimulating factors (CSFs), including GM-CSF, Meg-CSF, and G-CSF.

    Effects of Cytokines on Stem Cells

    • Influence multilineage potential and differentiation of specific cell types.
    • May require combinations with other factors and can prevent apoptosis.

    Granulocyte Colony-Stimulating Factor (G-CSF)

    • Major cytokine for stimulating neutrophil production.

    Neutrophil Development

    • Myeloblasts are the earliest stage in neutrophil maturation; their characteristics include:

      • Size: 14 to 20 μm
      • N:C ratio: 8:1 to 4:1
      • Typically found at 0% to 3% in bone marrow nucleated cells.

    • Promyelocytes are larger (16 to 25 μm) and account for 1% to 5% of nucleated cells, distinguished by:

      • Round to oval nucleus with 1-3 nucleoli.
      • Primary granules present, which are basophilic.

    Neutrophil Granule Types

    • Primary granules formed during the promyelocyte stage contain enzymes like myeloperoxidase and defensins.
    • Secondary granules appear during myelocyte and metamyelocyte stages and are specific for neutrophils.
    • Tertiary granules form during the metamyelocyte stage and contain substances like gelatinase and lysozyme.

    Neutrophil Kinetics

    • Neutrophil production rates: approximately 0.9 to 1.0 × 10^9 cells/kg per day.
    • Proliferative pool in the bone marrow contains about 2.1 × 10^9 cells/kg capable of division.
    • Maturation pool contains roughly 5.6 × 10^9 cells/kg, responsible for neutrophil maturation over about 6 days.

    Neutrophil Functions

    • Major roles include phagocytosis and destruction of microorganisms and foreign materials through:
      • Chemotaxis: Movement towards chemical signals produced by pathogens or damaged cells.
      • Diapedesis: Migration through the endothelium to reach the site of infection.

    Neutrophil Life Span and Pools

    • The half-life in blood is around 7 hours, but inflammation can prolong it.
    • Circulating neutrophils are categorized into:
      • Circulating neutrophil pool (CNP)
      • Marginated neutrophil pool (MNP), found along capillary walls.

    Mechanisms of Neutrophil Recruitment and Action

    • Capture and adhesion are mediated by endothelial activation and expression of E-selectin and CD18 integrin.
    • Neutrophil extracellular traps (NETs) are formed from DNA and serve to trap and kill pathogens.

    Summary of neutrophil morphological features during maturation

    • Myeloblast: identifiable structure with no granules.
    • Promyelocyte: presence of primary granules.
    • Myelocyte: emergence of secondary granules leading to the "dawn of neutrophilia."
    • Metamyelocyte: kidney-shaped nucleus with clumped chromatin; begins tertiary granule formation.

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    Description

    This quiz covers the recognition of hematopoietic stem cells (HSCs) through flow cytometry, their properties, and the role of cytokines in neutrophil production. Explore essential growth factors and their functions in the hematopoietic system.

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