Immune Response Types and Cells
104 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What are the primary components of innate immunity?

  • Interferons and antibodies
  • Epithelial barriers, phagocytic cells, and NK cells (correct)
  • T lymphocytes and B lymphocytes
  • Antibodies and cytokines

    • Which type of immunity is responsible for defense against intracellular microbes?

  • Humoral immunity
  • Passive immunity
  • Cell-mediated immunity (correct)
  • Natural immunity

    • What is the CD4:CD8 ratio in T-lymphocytes?

  • 3:1
  • 4:1
  • 1:1
  • 2:1 (correct)

    • Which T-helper cell subset produces IL-4, IL-5, and IL-13?

    <p>TH2 subset</p> Signup and view all the answers

    What do CD4 molecules bind to?

    <p>Class II MHC molecules</p> Signup and view all the answers

    What is the main function of phagocytic cells in innate immunity?

    <p>Engulf and destroy microbes</p> Signup and view all the answers

    What is the role of the CD3 complex in T-lymphocytes?

    <p>Signal transduction</p> Signup and view all the answers

    What type of immunity is characterized by its ability to recognize nonmicrobial substances?

    <p>Adaptive immunity</p> Signup and view all the answers

    Which cells mediate humoral immunity?

    <p>B lymphocytes</p> Signup and view all the answers

    Which cytokine is synthesized and secreted by TH1 cells?

    <p>IL-2</p> Signup and view all the answers

    What percentage of peripheral blood lymphocytes do natural killer cells (NK cells) make up?

    <p>10-15%</p> Signup and view all the answers

    Which of the following is a receptor used to identify NK cells?

    <p>CD16</p> Signup and view all the answers

    What is the primary role of natural killer cells?

    <p>To kill tumor cells and virally-infected cells</p> Signup and view all the answers

    Class I MHC molecules are present on which of the following?

    <p>All nucleated cells and platelets</p> Signup and view all the answers

    What type of antigens do class II MHC molecules present?

    <p>Exogenous antigens</p> Signup and view all the answers

    Which of the following statements about CD8+ T cells is true?

    <p>They are class I MHC-restricted.</p> Signup and view all the answers

    The genes encoding MHC molecules are clustered on which chromosome segment?

    <p>Chromosome 6</p> Signup and view all the answers

    NK cells secrete which cytokine to aid in immune response?

    <p>IFN-γ</p> Signup and view all the answers

    What type of maturation do CD4+ T cells undergo with class II MHC?

    <p>They do not mature without interaction with MHC.</p> Signup and view all the answers

    Which categories are MHC gene products classified into?

    <p>Class I, Class II, Class III</p> Signup and view all the answers

    What is the primary function of CD8+ T cells?

    <p>Kill other cells</p> Signup and view all the answers

    What is required for complete activation of T cells?

    <p>Engagement of TCR and interaction of CD28 with CD80/CD86</p> Signup and view all the answers

    Which immunoglobulin constitutes 95% of plasma immunoglobulins after B-cell activation?

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

    Which role is NOT associated with macrophages in the immune response?

    <p>Synthesize immunoglobulins</p> Signup and view all the answers

    Where are B-lymphocytes primarily found in the spleen?

    <p>White pulp</p> Signup and view all the answers

    Which immunoglobulin is primarily found as a monomer on the surface of B-cells?

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

    What do dendritic cells and Langerhan's cells have in common?

    <p>They contain large amounts of class II MHC molecules</p> Signup and view all the answers

    What happens to T cells in the absence of the second signal for activation?

    <p>They undergo apoptosis or become anergic</p> Signup and view all the answers

    What role do follicular dendritic cells serve in the germinal centers?

    <p>They contain antibodies on their cell surfaces</p> Signup and view all the answers

    What is the function of CD21 on B cells?

    <p>Serves as a complement receptor</p> Signup and view all the answers

    What characterizes the immediate phase of a Type I hypersensitivity reaction?

    <p>Vasodilatation and exudation</p> Signup and view all the answers

    What is a common consequence of a Type II hypersensitivity reaction?

    <p>Destruction through opsonization</p> Signup and view all the answers

    In which hypersensitivity reaction is cell-mediated immunity primarily involved?

    <p>Type IV hypersensitivity</p> Signup and view all the answers

    What type of hypersensitivity is characterized by the deposition of immune complexes in tissues?

    <p>Type III</p> Signup and view all the answers

    Which of the following is an example of Type II hypersensitivity?

    <p>Myasthenia gravis</p> Signup and view all the answers

    Which cells are primarily involved in the delayed-type hypersensitivity of Type IV hypersensitivity reactions?

    <p>CD4+ T cells</p> Signup and view all the answers

    What mechanism is associated with antibody-dependent cellular cytotoxicity (ADCC)?

    <p>Target cell lysis by cytotoxic cells</p> Signup and view all the answers

    What time frame characterizes the late phase of a Type I hypersensitivity reaction?

    <p>2-4 hours after exposure</p> Signup and view all the answers

    Which of the following conditions is associated with Type III hypersensitivity?

    <p>Serum sickness</p> Signup and view all the answers

    Which statement regarding Type I hypersensitivity is correct?

    <p>It results in immediate symptoms.</p> Signup and view all the answers

    What characterizes the late phase of a Type I hypersensitivity reaction?

    <p>Inflammation due to leukocyte influx</p> Signup and view all the answers

    Which of the following is a mechanism of Type II hypersensitivity reactions?

    <p>Opsonization and cell-mediated phagocytosis</p> Signup and view all the answers

    What type of hypersensitivity reaction is mediated by antigen-activated T lymphocytes?

    <p>Type IV</p> Signup and view all the answers

    Which condition is commonly associated with Type III hypersensitivity reactions?

    <p>Systemic lupus erythematosus</p> Signup and view all the answers

    Which of the following best describes the role of antibody-mediated cellular dysfunction in Type II hypersensitivity?

    <p>Disrupting normal cellular functions</p> Signup and view all the answers

    How do antigen-antibody complexes primarily cause damage in Type III hypersensitivity?

    <p>By eliciting inflammation at deposition sites</p> Signup and view all the answers

    What duration characterizes the immediate phase of a Type I hypersensitivity reaction?

    <p>5-30 minutes</p> Signup and view all the answers

    What is a common example of an autoimmune condition associated with Type II hypersensitivity?

    <p>Autoimmune hemolytic anemia</p> Signup and view all the answers

    What main role do T-lymphocytes serve in the adaptive immune response?

    <p>Regulate the immune response and perform cellular defense</p> Signup and view all the answers

    What is the primary function of T-helper-2 (TH2) cells?

    <p>Produce cytokines like IL-4, IL-5, and IL-13</p> Signup and view all the answers

    Which of the following describes the CD4+ T cells' interaction with MHC molecules?

    <p>Bind to class II MHC molecules on antigen-presenting cells</p> Signup and view all the answers

    How does somatic rearrangement affect TCR diversity?

    <p>It enables the creation of diverse antigen receptors</p> Signup and view all the answers

    What characterizes innate immunity?

    <p>It consists of defense mechanisms present before infection</p> Signup and view all the answers

    What is a major characteristic of B lymphocytes in humoral immunity?

    <p>They secrete antibodies into circulation</p> Signup and view all the answers

    Which statement about T-cell receptors (TCR) is accurate?

    <p>TCRs consist of α and β chains connected by disulfide bonds</p> Signup and view all the answers

    What defines the adaptive immune response's ability to recognize antigens?

    <p>It can specifically adapt to both microbial and nonmicrobial substances</p> Signup and view all the answers

    What is the primary identifying marker for natural killer (NK) cells?

    <p>CD56</p> Signup and view all the answers

    How do NK cells recognize target cells?

    <p>Using a combination of activator and inhibitor receptors</p> Signup and view all the answers

    What type of antigens do class I MHC molecules typically present?

    <p>Intracellular viral proteins</p> Signup and view all the answers

    Which of the following molecules do CD4+ T helper cells recognize?

    <p>Class II MHC proteins</p> Signup and view all the answers

    Which part of the immune system does CD16 belong to?

    <p>NK cell activation</p> Signup and view all the answers

    Which class of MHC molecules is expressed on all nucleated cells?

    <p>Class I MHC</p> Signup and view all the answers

    What mechanisms are implicated in hypersensitivity reactions?

    <p>T cell responses and antibody responses</p> Signup and view all the answers

    What is one function of the Main Histocompatibility Complex (MHC)?

    <p>Present peptide fragments to T cells</p> Signup and view all the answers

    What is the primary role of CD8+ T cells?

    <p>To kill infected or cancerous cells</p> Signup and view all the answers

    Which molecules do B cells express that are critical for their function?

    <p>CD40 and CD19</p> Signup and view all the answers

    How do T cells undergo complete activation?

    <p>By binding to specific MHC-antigen complexes with coreceptors and receiving additional signals</p> Signup and view all the answers

    Which immunoglobulin is mainly found in traces in the serum?

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

    What is a key characteristic of dendritic cells?

    <p>They express a large amount of class II MHC molecules</p> Signup and view all the answers

    What happens to T cells that do not receive a second signal during activation?

    <p>They undergo apoptosis or become unreactive</p> Signup and view all the answers

    Which function is NOT associated with macrophages?

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

    Where do B-lymphocytes primarily reside in the lymph nodes?

    <p>In the superficial cortex</p> Signup and view all the answers

    Which statement accurately describes innate immunity?

    <p>Innate immunity is present before infection occurs.</p> Signup and view all the answers

    What is the primary function of T-lymphocytes?

    <p>To recognize and eliminate infected or abnormal cells.</p> Signup and view all the answers

    Which T-cell subset predominantly binds to class II MHC molecules?

    <p>CD4+ T cells</p> Signup and view all the answers

    Which cytokine is NOT produced by TH1 cells?

    <p>IL-4</p> Signup and view all the answers

    Which cell type is primarily responsible for humoral immunity?

    <p>B-lymphocytes</p> Signup and view all the answers

    What type of immunity arises from prior exposure to microbes?

    <p>Adaptive immunity</p> Signup and view all the answers

    What role does somatic rearrangement play in T-cell receptors?

    <p>It generates diversity among TCRs.</p> Signup and view all the answers

    Which of the following describes the CD4:CD8 ratio in T-cells?

    <p>2:1</p> Signup and view all the answers

    What is the initial time frame for the immediate phase of a Type I hypersensitivity reaction?

    <p>5-30 minutes</p> Signup and view all the answers

    Which mechanism is NOT involved in Type II hypersensitivity reactions?

    <p>Sensitized T lymphocyte activation</p> Signup and view all the answers

    What type of immune response is primarily associated with Type IV hypersensitivity?

    <p>Cell-mediated immunity</p> Signup and view all the answers

    Which condition is an example of a Type III hypersensitivity reaction?

    <p>Systemic lupus erythematosus</p> Signup and view all the answers

    What characterizes the late phase of a Type I hypersensitivity reaction?

    <p>Influx of leukocytes and lasts for days</p> Signup and view all the answers

    Which of the following describes the mechanism of tissue damage in Type III hypersensitivity?

    <p>Inflammation at sites of immune complex deposition</p> Signup and view all the answers

    What type of antibodies are primarily involved in Type II hypersensitivity reactions?

    <p>IgG and IgM antibodies</p> Signup and view all the answers

    In Type IV hypersensitivity, sensitized T cells mainly respond to which type of antigens?

    <p>Intracellular pathogens</p> Signup and view all the answers

    What is the main identifying marker for natural killer cells?

    <p>CD16</p> Signup and view all the answers

    Which class of MHC molecules presents endogenous antigens?

    <p>Class I</p> Signup and view all the answers

    Which statement best describes the activator and inhibitor receptors of NK cells?

    <p>Activator receptors help identify potentially harmful cells; inhibitor receptors ensure normal cells remain unharmed.</p> Signup and view all the answers

    What is the primary function of class II MHC molecules?

    <p>To present exogenous antigens to CD4+ T cells.</p> Signup and view all the answers

    Which cytokine do natural killer cells primarily secrete?

    <p>IFN-γ</p> Signup and view all the answers

    What primary role does CD8 perform in T cell activation?

    <p>Serves as a co-receptor for MHC class I interactions.</p> Signup and view all the answers

    Which of the following genes encode components of the complement system?

    <p>Class III genes</p> Signup and view all the answers

    Where are class I MHC molecules commonly expressed?

    <p>On all nucleated cells and platelets</p> Signup and view all the answers

    What are the primary functions of CD8+ T cells?

    <p>Killing other cells and secreting TH1 cytokines</p> Signup and view all the answers

    What is the role of B-cells after antigen stimulation?

    <p>Transform into plasma cells that secrete immunoglobulins</p> Signup and view all the answers

    What is required for the complete activation of T cells?

    <p>Engagement of TCR by MHC-antigen complex with CD4/CD8 and interaction with CD28</p> Signup and view all the answers

    Which statement accurately describes roles of macrophages?

    <p>Participate in antigen presentation and the production of cytokines</p> Signup and view all the answers

    What molecule does CD40 on B-cells interact with?

    <p>CD154 on activated T-lymphocytes</p> Signup and view all the answers

    Where are B-lymphocytes primarily located in lymph nodes?

    <p>In the superficial cortex</p> Signup and view all the answers

    Which differences exist between dendritic cells and Langerhan's cells?

    <p>Dendritic cells are located in lymphoid tissue, while Langerhan's cells are in the epidermis</p> Signup and view all the answers

    What is the consequence for T cells if they do not receive the second signal for activation?

    <p>They undergo apoptosis or become anergic</p> Signup and view all the answers

    Study Notes

    Immune Response Types

    • Innate Immunity: Pre-existing defenses that recognize microbes and protect against infections.
      • Components:
        • Epithelial barriers, e.g., skin
        • Phagocytic cells: neutrophils, macrophages
        • Natural killer (NK) cells
        • Complement system proteins
    • Adaptive (Acquired) Immunity: Activated by microbes and can recognize non-microbial substances (antigens).
      • Types:
        • Cell-Mediated Immunity: Targets intracellular microbes; mediated by T lymphocytes (thymus-derived)
        • Humoral Immunity: Targets extracellular microbes and their toxins; mediated by B lymphocytes (bone marrow-derived) and secreted antibodies.

    Immune Cells

    • T Lymphocytes (T Cells): 60-70% of circulating lymphocytes.
      • T Cell Receptor (TCR): Recognizes specific antigens; composed of α and β polypeptide chains
        • Variable region: Binds to antigen
        • Constant region: Links to CD3 complex
      • CD3 Complex: Involves in signal transduction for TCR activation.
      • Somatic Rearrangement: TCR gene rearrangements create diversity.
      • CD4 and CD8 Coreceptors:
        • CD4: Present in about 60% of T cells; binds to class II MHC molecules on antigen-presenting cells.
        • CD8: Present in about 30% of T cells; binds to class I MHC molecules.
      • T Helper (TH) Cells:
        • TH1: Secrete IL-2 and IFN-γ; involved in delayed hypersensitivity, macrophage activation.
        • TH2: Secrete IL-4, IL-5, and IL-13; aid in antibody production and eosinophil activation.
      • CD8+ Cytotoxic T Cells: Kill other cells, primarily in cell-mediated immunity.
      • T Cell Activation: Requires two signals:
        • Engagement of TCR by appropriate MHC-antigen complex with CD4 or CD8 coreceptors.
        • Interaction of CD28 on T cells with CD80 or CD86 on antigen-presenting cells.
        • Absence of the second signal: T cells undergo apoptosis or become unresponsive (anergic), preventing autoimmune reactions.
    • B Lymphocytes (B Cells): 10-20% of circulating lymphocytes.
      • B Cell Receptor (BCR): Monomeric IgM; serves as an antigen receptor on B cells.
      • Somatic Rearrangement: Immunoglobulin gene rearrangements result in unique antigen specificity.
      • Other B Cell Molecules: CD19, CD20, CD21 (complement receptor, EBV binding), CD40 (interacts with CD154 on activated T cells)
      • Differentiation:
        • Plasma Cells: Secrete antibodies (IgG, IgM, IgA, IgE).
    • Macrophages: Role in immune response:
      • Antigen presentation to T cells via class II MHC molecules.
      • Cytokine production to influence other immune cells (T cells, B cells, endothelial cells, fibroblasts).
      • Secretion of toxic metabolites and enzymes to kill tumor cells.
      • Effector cells in delayed hypersensitivity reactions.
    • Dendritic Cells and Langerhan's Cells: Dendritic cell processes and high expression of class II MHC molecules.
      • Dendritic Cells: Found in lymphoid tissue.
      • Langerhan's Cells: Found in the epidermis.
      • Efficient Antigen Presentation: Low phagocytic activity.
      • Follicular Dendritic Cells: Found in germinal centers; express antibodies on their surface and have Fc receptors.
    • Natural Killer (NK) Cells: 10-15% of peripheral blood lymphocytes; not express TCR or immunoglobulin.
      • Larger Than Small Lymphocytes: Contains azurophilic granules (large granular lymphocytes).
      • Part of Innate Immunity: Kill tumor and virally infected cells without prior sensitization.
      • Identification: CD16 (Fc receptor for IgG-coated cells) and CD56.
      • Receptors:
        • Activators: Recognize ill-defined molecules on abnormal cells.
        • Inhibitors: Recognize class I MHC on normal cells.
      • Secrete IFN-γ:
    • Antibody-Dependent Cell Mediated Cytotoxicity (ADCC): NK cells kill antibody-coated cells via CD16.

    Major Histocompatibility Complex (MHC)

    • Function: Present peptide fragments of foreign proteins to T cells.
    • MHC Gene Location: Clustered on chromosome 6 (Human Leukocyte Antigen - HLA).
    • MHC Molecules:
      • Class I:
        • Expressed on all nucleated cells and platelets.
        • Encoded by HLA-A, HLA-B, and HLA-C loci.
        • Present endogenous antigens (e.g., viral proteins) to CD8+ cytotoxic T cells.
      • Class II:
        • Encoded by HLA-DP, HLA-DQ, and HLA-DR regions.
        • Present exogenous antigens (e.g., extracellular microbes) to CD4+ helper T cells.
      • Class III: Encode components of the complement system.

    Hypersensitivity Reactions (Types)

    • Type I (Immediate) Hypersensitivity: Rapid immune reaction within minutes of antigen-antibody binding to mast cells in previously sensitized individuals.
      • Phases:
        • Immediate Phase: Vasodilatation and exudation (5-30 minutes, subsiding in 60 minutes).
        • Late Phase: Leukocyte influx (2-4 hours, lasting for days)
      • Examples: Anaphylaxis, bronchial asthma, allergic rhinitis.
    • Type II Hypersensitivity: Antibodies against antigens on cell surfaces or extracellular matrix.
      • Mechanisms of Destruction:
        • Opsonization and Fc receptor-mediated phagocytosis.
        • Antibody-dependent cellular cytotoxicity (ADCC).
        • Antibody-mediated cellular dysfunction.
      • Examples:
        • Transfusion reactions
        • Autoimmune hemolytic anemia
        • Drug reactions
        • Myasthenia gravis
        • Grave's disease
        • Glomerulonephritis
        • Organ rejection
    • Type III Hypersensitivity: Immune complex (antigen-antibody) deposition in tissues causing inflammation and damage.
      • Examples:
        • Systemic lupus erythematosus
        • Polyarteritis nodosa
        • Poststreptococcal glomerulonephritis
        • Serum sickness.
    • Type IV (Cell-Mediated) Hypersensitivity: Initiated by antigen-activated T lymphocytes.
      • Mechanisms:
        • Delayed type hypersensitivity (CD4+ T cells): Defense against intracellular pathogens (e.g., mycobacteria, fungi, parasites).
        • Direct cell cytotoxicity (CD8+ T cells): Graft rejection.
      • Examples:
        • Contact dermatitis
        • Tuberculin reaction
        • Transplant rejection
        • Tumor immunity.

    The Immune Response

    • Innate immunity comprises defenses present before infection. It includes epithelial barriers, phagocytic cells, NK cells, and complement system proteins.
    • Adaptive immunity is stimulated by infection and can recognize microbes and nonmicrobial substances (antigens).
    • Cell-mediated immunity protects against intracellular microbes and is mediated by T lymphocytes.
    • Humoral immunity protects against extracellular microbes and toxins and is mediated by B lymphocytes and antibodies.

    Cells of the Immune System

    • T-lymphocytes

      • 60-70% of circulating lymphocytes.
      • Found in lymph nodes and spleen.
      • Contain a T cell receptor (TCR) composed of α and β chains with variable and constant regions.
      • Express CD4 or CD8 as coreceptors.
      • CD4+ T cells bind to class II MHC molecules and include TH1 (IL-2 and IFN-γ) and TH2 (IL-4, IL-5, and IL-13) subsets.
      • CD8+ T cells bind to class I MHC molecules and mainly function as cytotoxic cells.
      • T cell activation requires TCR engagement with MHC-antigen complex and CD28 interaction with CD80/CD86.

    • B-lymphocytes

      • 10-20% of circulating lymphocytes.
      • Found in lymph nodes and spleen.
      • Transform into plasma cells secreting antibodies.
      • Express a B cell receptor (BCR) composed of monomeric IgM.
      • Express CD19, CD20, CD21, and CD40.

    • Macrophages

      • Present antigens to T cells via class II MHC molecules.
      • Produce cytokines influencing other immune cells.
      • Secrete toxic metabolites and enzymes.
      • Important effector cells in delayed hypersensitivity.

    • Dendritic and Langerhans' cells

      • Have dendritic processes and high class II MHC expression.
      • Found in lymphoid tissue (dendritic) and epidermis (Langerhans).
      • Efficient antigen presenters with poor phagocytic activity.
      • Follicular dendritic cells in germinal centers trap antibodies.

    • Natural killer cells (NK cells)

      • 10-15% of peripheral blood lymphocytes.
      • Lack TCR and immunoglobulin.
      • Larger than lymphocytes and contain azurophilic granules.
      • Kill tumor and virally infected cells without prior sensitization.
      • Express CD16 and CD56.
      • Possess activating receptors and inhibitory receptors that recognize class I MHC.

    Major Histocompatibility Complex (MHC)

    • MHC molecules bind peptide fragments of foreign proteins for presentation to T cells.

    • Located on chromosome 6 and classified into class I, class II, and class III.

    • Class I MHC

      • Expressed on all nucleated cells and platelets.
      • Bind peptides derived from intracellular proteins (e.g., viral antigens).
      • Recognized by CD8+ cytotoxic T cells (class I MHC-restricted).

    • Class II MHC

      • Encoded by HLA-DP, HLA-DQ, and HLA-DR.
      • Present exogenous antigens (e.g., extracellular microbes).
      • Recognized by CD4+ helper T cells (class II MHC-restricted).

    Hypersensitivity Reactions

    • Type I (immediate) hypersensitivity: Rapid reaction (minutes) triggered by antigen-antibody binding to mast cells.

      • Immediate phase (5-30 min): Vasodilatation and exudation due to vasoactive amine release.
      • Late phase (2-4 hours): Influx of leukocytes (bronchial asthma, allergic rhinitis).

    • Type II hypersensitivity: Antibody-mediated against cell surface or extracellular matrix antigens.

      • Mechanisms: Opsonization and phagocytosis, antibody-dependent cell cytotoxicity (ADCC), antibody-mediated cellular dysfunction.
      • Examples: Transfusion reactions, autoimmune hemolytic anemia, drug reactions, myasthenia gravis, Grave's disease, glomerulonephritis, organ rejection.

    • Type III hypersensitivity: Immune complex-mediated.

      • Complexes deposit in various organs, primarily blood vessels.
      • Examples: Systemic lupus erythematosus, polyarteritis nodosa, poststreptococcal glomerulonephritis, serum sickness.

    • Type IV hypersensitivity (cell-mediated): Initiated by antigen-activated T lymphocytes.

      • Delayed type hypersensitivity: Mediated by CD4+ T cells, involved in defense against intracellular pathogens (mycobacteria, fungi, parasites), transplant rejection, tumor immunity.
      • Direct cell cytotoxicity: Mediated by CD8+ T cells, mainly encountered in graft rejection.

    Immune Response

    • Two major types of immune response: innate and adaptive
    • Innate immunity: present at birth, non-specific defense against pathogens
      • Components: epithelial barriers, phagocytes (neutrophils and macrophages), natural killer (NK) cells, complement system proteins
    • Adaptive immunity: develops after exposure to pathogens, highly specific
      • Two types: cell-mediated and humoral immunity

    Cells of the Immune System

    • T-lymphocytes (T cells): key players in cell-mediated immunity, originate in bone marrow and mature in thymus
      • T cell receptor (TCR): recognizes specific antigens
      • CD4 and CD8: coreceptors on T cells, determine which MHC class they interact with
      • CD4+ T cells: helper T cells, promote immune response by secreting cytokines
      • CD8+ T cells: cytotoxic T cells, directly kill infected or cancerous cells
    • B-lymphocytes (B cells): key players in humoral immunity, originate in bone marrow
      • Antibodies (immunoglobulins): secreted proteins that bind to antigens, neutralizing or eliminating pathogens
      • B cell receptor (BCR): recognizes specific antigens
      • Plasma cells: mature B cells that secrete antibodies
    • Macrophages: phagocytose foreign material and pathogens, present antigens to T cells
      • Produce cytokines: proteins that influence the behavior of other immune cells
      • Secrete toxic metabolites and enzymes: for killing tumor cells
    • Dendritic cells: antigen-presenting cells with dendritic processes
      • Efficient antigen presentation: activate T cells
      • Found in various tissues: lymph nodes, skin (Langerhan's cells)
    • Natural killer (NK) cells: part of innate immunity, kill infected or cancerous cells without prior sensitization
      • Don't express TCR or immunoglobulins: use other mechanisms for target recognition
      • Secrete IFN-γ: immune-stimulating cytokine

    Major Histocompatibility Complex (MHC)

    • MHC proteins: expressed on cell surfaces, present antigen fragments to T cells
    • Class I MHC: expressed on all nucleated cells, presents antigens from inside the cell (e.g., viral proteins)
      • Recognized by CD8+ T cells
    • Class II MHC: expressed on antigen-presenting cells (macrophages, dendritic cells), presents antigens from outside the cell (e.g., bacterial proteins)
      • Recognized by CD4+ T cells

    Hypersensitivity Reactions

    • Hypersensitivity: exaggerated or inappropriate immune response to an antigen, causing tissue damage
    • Type I (Immediate): mediated by IgE antibodies binding to mast cells, triggering immediate release of histamine and other inflammatory mediators
      • Examples: allergies, anaphylaxis
    • Type II (Cytotoxic): mediated by antibodies directed against cell surface antigens, leading to cell lysis or dysfunction
      • Examples: transfusion reactions, autoimmune hemolytic anemia
    • Type III (Immune Complex-mediated): mediated by antigen-antibody complexes depositing in tissues, triggering inflammation and tissue damage
      • Examples: systemic lupus erythematosus, serum sickness
    • Type IV (Cell-mediated): mediated by T cell activation, leading to delayed tissue damage
      • Examples: contact dermatitis, graft rejection, tuberculin skin test

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Immune System PDF

    Description

    Explore the fundamental aspects of the immune response, including both innate and adaptive immunity. Understand the key roles of various immune cells such as T lymphocytes and their functions in recognizing specific antigens. This quiz will test your knowledge on immune defenses and cell-mediated processes.

    More Like This

    Adaptive Immunity
    20 questions

    Adaptive Immunity Quiz: Boost Your Knowledge

    IntuitiveSmokyQuartz2494 avatar
    IntuitiveSmokyQuartz2494
    Types of Immune Responses
    3 questions

    Types of Immune Responses

    HighSpiritedEuclid avatar
    HighSpiritedEuclid
    Cells of Adaptive Immunity
    55 questions

    Cells of Adaptive Immunity

    RejoicingSuccess avatar
    RejoicingSuccess
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser