Immunology Quiz: Leukocytes
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Questions and Answers

Which leukocyte comprises over 50% of all leukocytes and are identified as polymorphic leukocytes?

  • Monocytes
  • Basophils
  • Eosinophils
  • Neutrophils (correct)

    • Which type of leukocyte differentiates into macrophages when it migrates into tissues?

  • Monocytes (correct)
  • Neutrophils
  • Lymphocytes
  • Eosinophils

    • Which of the following is a function of basophils?

  • Producing antibodies.
  • Directly attacking virus-infected cells.
  • Phagocytizing bacteria in acute infections.
  • Releasing histamine to promote inflammation. (correct)

    • Eosinophils are most effective against which type of pathogen?

    <p>Parasitic worms</p> Signup and view all the answers

    Which leukocytes are primarily located in lymphoid tissue (lymph nodes, spleen, etc) rather than in the bloodstream?

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

    Which of the following is NOT a granulocyte?

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

    What is the primary function of T lymphocytes (T cells)?

    <p>Acting directly against virus-infected and tumor cells</p> Signup and view all the answers

    What is the role of B lymphocytes (B cells) in the immune system?

    <p>Giving rise to plasma cells that produce antibodies</p> Signup and view all the answers

    What primary role do interleukins and colony-stimulating factors play in the context of leukopoiesis?

    <p>They regulate the production of leukocytes based on the body's needs.</p> Signup and view all the answers

    Regarding the maturation and storage of granulocytes, what is accurate based on the provided information?

    <p>Bone marrow primarily stores mature granulocytes, typically containing significantly more than are found in circulating blood.</p> Signup and view all the answers

    How is leukemia characterized, and what are its primary effects on the body?

    <p>Leukemia is a cancer of white blood cells where unspecialized and mitotic cells overtake the bone marrow, leading to anemia and clotting problems.</p> Signup and view all the answers

    What is the typical treatment approach for leukemia?

    <p>Irradiation and administration of anti-leukemic drugs, potentially followed by a bone marrow transplant.</p> Signup and view all the answers

    What is indicated by the terms 'acute' and 'chronic' when classifying leukemia?

    <p>'Acute' indicates a rapid onset from blast-type cells, whereas 'chronic' indicates slower progression from cells at later stages.</p> Signup and view all the answers

    Which substance, found in both saliva and lacrimal fluid, helps to combat bacteria through its enzymatic action?

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

    What is the primary function of mucin in the respiratory and digestive tracts?

    <p>To trap microorganisms</p> Signup and view all the answers

    Which of the following is NOT a typical sign of inflammation?

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

    What is the role of inflammatory chemicals released during the inflammatory process?

    <p>To promote arteriole dilation and increase capillary leakiness.</p> Signup and view all the answers

    What is the primary function of interferon secreted by virus-infected cells?

    <p>To block protein synthesis and degrade viral RNA in nearby cells</p> Signup and view all the answers

    How does interferon contribute to anti-cancer effects?

    <p>By activating macrophages and mobilizing natural killer cells</p> Signup and view all the answers

    What is the complement system?

    <p>A group of at least 20 plasma proteins that amplify the inflammatory process</p> Signup and view all the answers

    What is the function of C3b, a component of the complement system?

    <p>It functions as an opsonin.</p> Signup and view all the answers

    Where do immature lymphocytes, known as B-cells, primarily undergo maturation?

    <p>Bone marrow</p> Signup and view all the answers

    What is the primary role of plasma cells in the humoral immune response?

    <p>Producing and secreting specific antibodies</p> Signup and view all the answers

    What is the fate of B-cell clones that do not differentiate into plasma cells during a humoral immune response?

    <p>They remain as memory cells that can be activated later.</p> Signup and view all the answers

    What is the defining characteristic of an immunocompetent lymphocyte?

    <p>Display of a unique receptor able to react to one &amp; only one foreign antigen</p> Signup and view all the answers

    Where does antigen challenge typically occur, leading to the activation of lymphocytes?

    <p>Spleen or lymph node</p> Signup and view all the answers

    What is the primary function of pyrogens in the context of fever?

    <p>To reset and elevate the body's thermostat.</p> Signup and view all the answers

    Why is a moderate fever considered helpful in fighting infection?

    <p>It speeds up the metabolic rate and sequesters iron and zinc, hindering bacterial growth.</p> Signup and view all the answers

    What is the role of MHC I (major histocompatibility complex) in the context of natural killer (NK) cells?

    <p>MHC I inhibits NK cells, preventing them from attacking healthy cells that express sufficient MHC I.</p> Signup and view all the answers

    How do natural killer (NK) cells recognize and target virus-infected or cancerous cells?

    <p>By detecting a combination of stress marker expression and a lack of protective MHC I.</p> Signup and view all the answers

    Which of the following is NOT a key player in adaptive immune mechanisms?

    <p>Natural killer cells</p> Signup and view all the answers

    What is the function of the major histocompatibility complex (MHC)?

    <p>To mark a cell as “self” and present antigens.</p> Signup and view all the answers

    Where do T-cells mature and what two crucial traits do they acquire during this process?

    <p>Thymus; immunocompetence and self-tolerance.</p> Signup and view all the answers

    What is the origin of lymphocytes, and what initially determines whether a lymphocyte will become a B- or T-lymphocyte?

    <p>Red bone marrow; the location where it matures.</p> Signup and view all the answers

    What is the primary cause of infectious mononucleosis?

    <p>Epstein-Barr virus.</p> Signup and view all the answers

    Which of the following best describes leukopenia?

    <p>An abnormally low white blood cell count.</p> Signup and view all the answers

    What distinguishes innate (nonspecific) defenses from adaptive (specific) defenses?

    <p>Innate defenses do not require specific identification of foreign substances, while adaptive defenses do.</p> Signup and view all the answers

    Which of the following is an example of a DAMP (Damage-Associated Molecular Pattern)?

    <p>DNA in the cytoplasm.</p> Signup and view all the answers

    What is the role of Toll-like receptors in the innate immune system?

    <p>Recognizing PAMPs to trigger phagocytosis and inflammation.</p> Signup and view all the answers

    How do PAMPs and DAMPs contribute to the immune response?

    <p>They activate the innate immune system by indicating something is wrong, without needing specific recognition of a microorganism.</p> Signup and view all the answers

    What is the primary feature of adaptive immunity?

    <p>Targeted immune response carried out by specific lymphocyte subpopulations.</p> Signup and view all the answers

    Which event would likely trigger the release of DAMPs?

    <p>A sprained ankle.</p> Signup and view all the answers

    Study Notes

    Innate Immunity

    • Protects against foreign substances/abnormal cells without identifying them using generalized carbohydrate/lipid cell surface markers.
    • Features include opsonization, lysis of pathogens, chemotaxis, inflammation, and cell activation.

    Adaptive Immunity

    • Acquired immunity involving lymphocyte subpopulations.
    • Recognizes specific cell surface proteins.
    • Subclones itself to create a targeted immune response through different mechanisms.

    Complement System

    • Composed of at least 20 plasma proteins.
    • Activated components amplify inflammatory responses.
    • Features include direct destruction of invading microbes (membrane attack complex), vasodilation and increased permeability of capillaries/venules, chemotaxis, and enhancement of phagocytosis.

    Innate Defenses

    • Skin and mucous membranes.

      • Acidic secretions (skin, vagina, stomach) deter bacterial growth
      • Enzymes (lysozyme in saliva, respiratory mucus, lacrimal fluid, protein-digesting enzymes in stomach) also act as defenses
      • Mucin traps microorganisms
      • Defensins—broad-spectrum antimicrobial peptides secreted by mucous membranes and skin.

    • Other chemicals such as lipids that are toxic to bacteria.

    Inflammation

    • Response to injury—characterized by redness, heat, swelling, and pain.
    • Prevents spread of microorganisms to nearby tissues.
    • Disposes of cell debris and pathogens.
    • Sets the stage for repair processes.
    • Alerts the adaptive immune system.
    • Inflammatory chemicals (e.g., histamine, kinins, prostaglandins, complement) are released; activate inflammation; and promote arteriole dilation, capillary leakiness.
    • Also attracts immune cells to the injury/infection site.

    Interferon

    • Secreted by virus-infected cells to diffuse to nearby non-infected cells.
    • Blocks protein synthesis and degrades viral RNA.
    • Activates macrophages and natural killer cells to fight foreign invaders.

    Natural Killer (NK) Cells

    • Part of the innate immune system.
    • Not specific to a particular antigen.
    • Attack virus-infected and cancer cells.
    • Triggered by a combination of cell stress marker expression and lack of protective MHC 1.
    • Cells infected with viruses or cancer reduce their expression of MHC 1(major histocompatibility complex).

    Leukocytes

    • Formed elements in complete blood cells (less than 1% of total volume).
      • Usually 4,800-10,800 per microliter (WBC)
      • Protect against bacteria, viruses, parasites, toxins, and tumor cells.
      • Can leave the bloodstream to mount immune or inflammatory responses.
      • Leukocytosis (count > 11,000/µL)—body's response to bacterial or viral invasion; number can double within hours.
      • Granulocytes and Agranulocytes -Granulocytes: neutrophils, eosinophils, and basophils -Agranulocytes: lymphocytes and monocytes

    Granulocytes

    • Neutrophils (50–70%): phagocytes that ingest and destroy bacteria (acute infections)
    • Eosinophils (2-4%): target parasitic worms and modulate immune responses, allergies, and asthma.
    • Basophils (0.5–1%): rarest WBCs with granules containing histamine (vasodilator).

    Agranulocytes

    • Lymphocytes (25–45%): a second most common leukocyte that have dark purple nuclei and pale blue cytoplasm, lymphocytes are found in lymph nodes, spleen and so on. T-cells and B-cells.
      • T cells: directly attack virus-infected cells or tumor cells.
      • B cells: generate plasma cells that produce antibodies.
    • Monocytes (3-8%): largest leukocytes. In tissues, differentiate into macrophages. Phagocytic in chronic infections (e.g., TB).

    Fever

    • Body's thermostat normally set at 37°C.
    • Reset by pyrogens released from leukocytes and macrophages exposed to bacteria or other foreign substances.
    • Moderate fever is helpful: speeds up metabolic rate, and causes liver and spleen to sequester iron and zinc.
    • High fevers can be dangerous.

    T-cells

    • Migrate to thymus for maturation (2–3 days).
    • Acquire immunocompetence and self-tolerance.
    • Only about 2% of T cells succeed in maturation.
    • Positive selection: T cells recognize self-MHC proteins. Failure to recognize leads to apoptosis.
    • Negative selection: T cells must not recognize self-antigens. Failure to not recognize leads to survival.

    B-cells

    • Immature lymphocytes mature in bone marrow.
    • Self-reactive lymphocytes are removed.
    • Display unique receptors on cells to react to foreign antigens.
    • Differentiate into plasma cells, which produce antibodies; or become memory cells able to initiate a secondary defense (usually faster).

    Adaptive Mechanisms

    • B lymphocytes (humoral immunity)
    • T lymphocytes (cell-mediated immunity)
    • Macrophages (antigen-presenting cells)

    Lymphocytes

    • Originate in red bone marrow.
    • Initially identical.
    • Mature into B or T lymphocytes based on their maturation location.
    • Immunocompetence—able to recognize its specific antigens; self-tolerance—does not react to "self" antigens.

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    ANP1115 Lecture 6: Immune System Part 1 PDF

    Description

    Test your knowledge on the different types of leukocytes and their functions in the human immune system. This quiz covers topics including the characteristics of granulocytes, lymphocytes, and their roles in leukopoiesis and diseases such as leukemia. Challenge yourself to identify each type and its importance!

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