Immunology and Inflammation Quiz
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Questions and Answers

What are the two main components of immunity mentioned in the text?

  • Physical and Physiologic
  • Adaptive and Acquired
  • Innate and Adaptive (correct)
  • Specific and Nonspecific

    • What is the major agent of adaptive immunity mentioned in the text?

    lymphocytes

    The outer epidermal layer of the skin is filled with a waterproofing protein called _______.

    keratin

    Innate immunity is uniform in all members of a species.

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

    Match the following cardinal signs of inflammation with their descriptions:

    <p>Rubor = Redness Tumor = Swelling Calor = Heat Dolor = Pain</p> Signup and view all the answers

    What is the main function of C-reactive protein in response to tissue damage?

    <p>All of the above</p> Signup and view all the answers

    Histamine causes vasoconstriction and decreased permeability in nearby blood vessels.

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

    What is the substance formed from the accumulation of dead cells, digested material, and fluid at an infection site?

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

    Tissue injury activates small peptides in blood plasma called ______, resulting in vasodilation and increased capillary permeability.

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

    Match the following components to their functions:

    <p>Histamine = Causes vasodilation and increased permeability of blood vessels Bradykinin = Stimulates pain receptors and increases capillary permeability Fibrin = Forms insoluble strands in the blood clot to wall off the injured area Antibodies = Effector molecules of humoral immunity that bind to and neutralize antigens</p> Signup and view all the answers

    In the humoral immune response, B cells differentiate into __________.

    <p>Antibody-secreting plasma cells</p> Signup and view all the answers

    What are the regions on an antigen called that bind to B-cell or T-cell receptors?

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

    Antigen recognition by T cells is influenced by the particular set of alleles that an individual inherits.

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

    In order for a foreign protein antigen to be recognized by a T cell, it must be degraded into small _________ that form complexes with class I or class II MHC molecules.

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

    Match the following immune system molecules with their role in antigen recognition:

    <p>Membrane-bound antibodies on B cells = Recognize antigen directly T-cell receptors = Bind to T-cell antigenic peptides Class I MHC molecules = Present antigen to CD8 T cells Class II MHC molecules = Present antigen to CD4 T cells</p> Signup and view all the answers

    What causes the rejection of transplanted organs by the immune system?

    <p>Failure to recognize the organ as self</p> Signup and view all the answers

    Autoimmunity can lead to chronic debilitating diseases.

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

    What is the term for the condition where the immune system malfunctions by losing its sense of self and nonself?

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

    In acquired immune deficiency syndrome (AIDS), T helper cells are infected and destroyed by ____________, causing a collapse of the immune system.

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

    Match the following terms with the correct definitions:

    <p>Immunogenicity = Ability to induce a humoral and/or cell-mediated immune response Antigenicity = Ability to combine specifically with antibodies and/or cell-surface receptors Haptens = Small molecules antigenic but incapable of inducing immune response</p> Signup and view all the answers

    Which cells recognize lipids arising from Mycobacterium tuberculosis and Mycobacterium leprae?

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

    Large, insoluble macromolecules are less immunogenic than small, soluble ones.

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

    What is the primary role of adjuvants in immunization?

    <p>enhance the immunogenicity of antigens</p> Signup and view all the answers

    Antigen persistence is prolonged when mixed with ________.

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

    What determines the shape of the epitope for globular protein antigens?

    <p>The tertiary conformation of the native protein</p> Signup and view all the answers

    Larger areas of protein antigens are typically engaged by the antibody binding site.

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

    What type of amino acids are protruding regions that are likely to be recognized as epitopes composed of?

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

    Epitopes may be composed of sequential contiguous residues along the _______.

    <p>polypeptide chain</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Haptens = Small organic molecules that are antigenic but not immunogenic MHC molecules = Present antigenic peptides to T cells Immunodominant epitopes = Induce a more pronounced immune response than other epitopes T-cell epitopes = Interact with both a T-cell receptor and an MHC molecule</p> Signup and view all the answers

    What is the function of IgE antibodies?

    <p>Release histamine and other mediators of inflammation upon antigen binding</p> Signup and view all the answers

    Is IgD able to fix complement and cross the placenta?

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

    What is the basic structure of the immunoglobulin fold?

    <p>A 'sandwich' of two pleated sheets connected by loops</p> Signup and view all the answers

    What type of receptors do antibodies and T-cell receptors belong to in the immune system?

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

    What is the role of sIgA in the small intestine?

    <p>binds to antigens within the mucosal layer, excretes antigen-sIgA complexes into the gut lumen, and plays a role in the alternative complement pathway.</p> Signup and view all the answers

    Immunoglobulin folds are stabilized by hydrogen bonds within a single sheet.

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

    What are the regions on the loops that connect the strands of the VH and VL domains called?

    <p>complementarity determining regions (CDRs)</p> Signup and view all the answers

    Pattern recognition receptors (PRRs) recognize broad structural motifs that are unique to the host.

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

    Isotypic determinants are constant-region determinants that define each heavy-chain class and subclass. Isotypes correspond to the variations in the heavy chain constant regions associated with the different classes present in all individuals. There are five isotypes corresponding to the ______ antibody classes.

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

    IgM is usually present in the bloodstream where it agglutinates bacteria, activates complement by the classical pathway, and enhances the ingestion of pathogens by ____________ cells.

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

    The ability of pattern-recognition receptors to distinguish between self and nonself is perfect because the molecular pattern targeted by the receptor is produced only by the ______ and never by the host.

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

    What are the two soluble pattern recognition receptors that bind to microbial surfaces and promote opsonization?

    <p>Mannose binding lectin (MBL) and C-reactive protein (CRP)</p> Signup and view all the answers

    Study Notes

    Immunity and the Immune System

    • Immunity is the state of protection from infectious diseases and has two components: innate immunity and adaptive immunity
    • Innate immunity provides the first line of defense against infection and is not specific to a particular pathogen
    • Innate immunity includes:
      • Phagocytic cells (macrophages and neutrophils)
      • Barriers (skin and mucous membranes)
      • Antimicrobial compounds synthesized by the host

    Physical Barriers

    • Skin:
      • Consists of two layers: epidermis (outer) and dermis (inner)
      • Epidermis contains tightly packed epithelial cells and a waterproofing protein called keratin
      • Dermis contains blood vessels, hair follicles, sebaceous glands, and sweat glands
    • Mucous membranes:
      • Line the conjunctivae, alimentary, respiratory, and urogenital tracts
      • Consist of an outer epithelial layer and an underlying layer of connective tissue

    Physiologic Barriers

    • Temperature:
      • Some species are not susceptible to certain diseases due to their high body temperature
    • pH:
      • Gastric acidity is an innate physiologic barrier to infection
      • Newborns are susceptible to some diseases due to their less acidic stomach contents

    Soluble Factors

    • Lysozyme:
      • A hydrolytic enzyme found in mucous secretions and tears that cleaves the peptidoglycan layer of bacterial cell walls
    • Interferon:
      • A group of proteins produced by virus-infected cells that induce a generalized antiviral state
    • Complement:
      • A group of serum proteins that circulate in an inactive state and can be activated to damage the membranes of pathogenic organisms

    Pattern Recognition

    • Many molecules involved in innate immunity have the ability to recognize specific patterns of molecules
    • Examples:
      • Toll-like receptors (TLRs) that recognize lipopolysaccharide (LPS) found on Gram-negative bacteria
      • Collectins that recognize and kill certain bacteria by disrupting their lipid membranes

    Phagocytosis

    • A type of endocytosis in which a cell's plasma membrane expands around particulate material to form large vesicles called phagosomes
    • Conducted by specialized cells such as blood monocytes, neutrophils, and tissue macrophages

    Inflammatory Response

    • A complex sequence of events triggered by tissue damage or invading pathogenic microorganisms
    • Characterized by:
      • Vasodilation and increased permeability of capillaries
      • Influx of fluid and cells from the engorged capillaries into the tissue
      • Phagocytosis by specialized cells
      • Release of chemical mediators such as histamine and kinins

    Adaptive Immunity

    • Capable of recognizing and selectively eliminating specific foreign microorganisms and molecules
    • Characterized by:
      • Antigenic specificity
      • Diversity
      • Immunologic memory
      • Self/non-self recognition

    Lymphocytes

    • Produced in the bone marrow by the process of hematopoiesis
    • Mediate the defining immunologic attributes of specificity, diversity, memory, and self/non-self recognition
    • Two major populations:
      • B lymphocytes (B cells)
      • T lymphocytes (T cells)

    B Cells

    • Mature within the bone marrow and express a unique antigen-binding receptor on its membrane
    • Produce antibodies in a secreted form that can recognize and bind to specific antigens

    T Cells

    • Mature within the thymus gland
    • Express a unique antigen-binding molecule, called the T-cell receptor, on its membrane
    • Recognize antigen that is bound to cell-membrane proteins called major histocompatibility complex (MHC) molecules### T Cells and Immune Response
    • T cells can be distinguished into T helper (TH) cells and T cytotoxic (TC) cells based on the presence of CD4 and CD8 membrane glycoproteins.
    • TH cells recognize antigen-MHC class II molecule complexes and secrete cytokines, which activate B cells, TC cells, macrophages, and other cells.
    • Activated TH cells produce cytokines, which result in different immune responses.
    • TC cells recognize antigen-MHC class I molecule complexes and become cytotoxic T lymphocytes (CTLs), which exhibit cell-killing activity.

    Humoral and Cell-Mediated Immunity

    • Humoral immunity refers to the protection conferred by serum antibodies from an immune individual.
    • Cell-mediated immunity can be transferred only by administration of T cells from an immune individual.
    • B cells interact with antigen, leading to antibody secretion, which neutralizes or facilitates the elimination of antigen.
    • Antibody functions as the effector of the humoral response, and its binding to antigen can lead to various mechanisms of elimination.

    Antigen Recognition

    • Lymphocytes recognize discrete sites on the antigen called antigenic determinants or epitopes.
    • B cells can recognize an epitope alone, while T cells recognize an epitope only when associated with an MHC molecule.
    • Each branch of the immune system is suited to recognize antigen in a different milieu.
    • The humoral branch (B cells) recognizes epitopes on the surface of bacteria, viral particles, and soluble proteins, while the cell-mediated branch (T cells) recognizes protein epitopes associated with MHC molecules.

    MHC Molecules

    • MHC molecules function as antigen-recognition molecules, but lack fine specificity for antigen.
    • Each MHC molecule can bind to a spectrum of antigenic peptides derived from the intracellular degradation of antigen molecules.
    • Different allelic forms of MHC molecules confer different structures on the antigen-binding cleft, influencing the ability to present antigen to T lymphocytes.

    Antigen Processing and Presentation

    • Antigen processing and presentation involve the degradation of proteins into small antigenic peptides that form complexes with MHC molecules.
    • Exogenous antigen is processed and presented with class II MHC molecules, while endogenous antigen is processed and presented with class I MHC molecules.

    Immune Dysfunction

    • Immune dysfunction can result in allergy, asthma, graft rejection, autoimmune disease, and immunodeficiency.
    • Allergy and asthma are caused by inappropriate immune responses to common antigens.
    • Autoimmune disease occurs when the immune system loses its sense of self and nonself, leading to an immune attack on the host.
    • Immunodeficiency can be caused by genetic abnormality or damage to immune components, resulting in varying degrees of disease severity.### Immunogens and Immune Response
    • Proteins are the most potent immunogens, followed by polysaccharides, while lipids and nucleic acids are not immunogenic unless complexed with proteins or polysaccharides.
    • Proteins and polysaccharides are commonly used as immunogens in experimental studies of humoral immunity.
    • For cell-mediated immunity, proteins, lipids, and glycolipids serve as immunogens, but they must be combined with MHC-like membrane molecules called CD1.

    Properties of Immunogens

    • Immunogenicity is not an intrinsic property of an antigen, but depends on several factors, including:
      • Foreignness: the degree of phylogenetic distance between the species from which the antigen is derived and the species being immunized.
      • Molecular size: larger molecules are more immunogenic than smaller ones.
      • Chemical composition and complexity: certain structures, such as branched chains, contribute to immunogenicity.
      • Ability to be processed and presented with MHC molecules: macromolecules that cannot be degraded and presented with MHC molecules are poor immunogens.

    Antigen Presentation and Recognition

    • T cells recognize peptides derived from protein antigens when presented as peptide-MHC complexes.
    • Lipids can also be recognized by T cells, specifically glycolipids and phospholipids, which are presented as complexes with CD1 molecules.
    • B cells recognize soluble antigens that bind to their membrane-bound antibody, and tend to recognize highly accessible sites on the exposed surface of the immunogen.

    Genetic Control of Immune Response

    • The genetic constitution of the recipient influences the type of immune response and the degree of response.
    • Genes within the MHC play a central role in determining the degree of response to an immunogen.
    • Other genes, such as those encoding B-cell and T-cell receptors, also affect the immunogenicity of a given macromolecule.

    Factors Affecting Immune Response

    • Dose and route of antigen administration: different doses and routes can induce different immune responses.
    • Adjuvants: substances that enhance the immunogenicity of an antigen, such as alum and Freund's adjuvants.
    • Genetic variability: differences in genes involved in immune response affect the immunogenicity of a given macromolecule.

    Epitopes and Antibody-Antigen Interactions

    • Epitopes are the immunologically active regions of an immunogen that bind to antigen-specific membrane receptors on lymphocytes or to secreted antibodies.
    • Lymphocytes recognize discrete sites on the macromolecule called epitopes, which can involve elements of the primary, secondary, tertiary, and quaternary structure of the protein.
    • Antibody binds to an epitope through weak noncovalent interactions, requiring complementary shapes and sizes.

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    Test your knowledge on the components of immunity, skin structure, and the role of C-reactive protein in response to tissue damage.

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