ch 4 part 2 Antibody Diversity and Specificity Quiz
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Questions and Answers

What are antibodies?

  • Antigen-binding proteins present on the B-cell membrane and secreted by plasma cells (correct)
  • Proteins that directly attack antigens
  • Proteins present on T-cell membrane and secreted by plasma cells
  • Proteins only present on the B-cell membrane

    • How does the immune system usually respond to complex antigens?

  • By producing a single antibody for the entire antigen
  • By activating T cells instead of producing antibodies
  • By producing antibodies to several epitopes on the antigen (correct)
  • By producing antibodies to only one epitope on the antigen

    • What are the outputs of B cells in response to complex antigens?

  • Polyclonal antibodies, each binding multiple antigenic determinants
  • Monoclonal antibodies, each binding multiple antigenic determinants
  • Monoclonal antibodies, each specifically binding a single antigenic determinant (correct)
  • Polyclonal antibodies, each specifically binding a single antigenic determinant

    • Where do antibodies reside?

    <p>In the serum</p> Signup and view all the answers

    What are antibodies also commonly referred to as?

    <p>Immunoglobulin (Ig)</p> Signup and view all the answers

    Which fraction of the blood contains red blood cells, leukocytes, and platelets?

    <p>Cellular fraction</p> Signup and view all the answers

    What is the common structure of antibody molecules?

    <p>Two identical light chains and two identical heavy chains</p> Signup and view all the answers

    What type of chains make up the structure of antibody molecules?

    <p>Light and heavy chains</p> Signup and view all the answers

    How many peptide chains make up the structure of antibody molecules?

    <p>Four peptide chains</p> Signup and view all the answers

    What type of bond links each light chain to a heavy chain in the antibody structure?

    <p>Disulfide bond</p> Signup and view all the answers

    What gives segmental flexibility to the immunoglobulin?

    <p>Hinge region rich in proline and cysteine residues</p> Signup and view all the answers

    What forms the basic four-chain antibody structure?

    <p>(H-L)2, a dimer of dimers</p> Signup and view all the answers

    What is the composition of the antigen-binding site of the antibody molecule?

    <p>Complementarity-determining regions (CDRs) on both light and heavy chains</p> Signup and view all the answers

    Which region of the immunoglobulin molecule differs from one antibody to another?

    <p>Variable (V) region</p> Signup and view all the answers

    How many amino acids typically make up the amino-terminal variable (V) region in each heavy and light chain of an immunoglobulin molecule?

    <p>100–110 amino acids</p> Signup and view all the answers

    What is the composition of the constant (C) region in heavy chain of an antibody molecule?

    <p>Three or four Ig domains</p> Signup and view all the answers

    Which region of the antibody molecule mediates most of the biological functions of antibodies?

    <p>Heavy chain C region</p> Signup and view all the answers

    Where are the membrane-bound antibodies in the plasma membranes of B lymphocytes attached?

    <p>Heavy chain C region</p> Signup and view all the answers

    How many sub isotypes of α heavy chains are there in humans?

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

    How many distinct classes and subclasses can antibody molecules be divided into based on differences in the structure of their heavy constant chain (HC) regions?

    <p>8</p> Signup and view all the answers

    How many sub isotypes of ϒ heavy chains are there in humans?

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

    What do hypervariable regions correspond to in antibody-antigen interaction?

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

    Where do smaller antigens fit in the variable regions of antibodies?

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

    How do larger antigens interact with the variable region of antibodies?

    <p>Flatter regions</p> Signup and view all the answers

    What is opsonization?

    <p>The promotion of phagocytosis of antigens by macrophages and neutrophils</p> Signup and view all the answers

    What initiates the signal-transduction pathway resulting in the phagocytosis of the antigen-antibody complex?

    <p>Crosslinking of the FcR by binding to an array of antibody</p> Signup and view all the answers

    What are protein molecules called that can bind the constant region of Ig molecules and are present on the surfaces of macrophages and neutrophils?

    <p>Fc receptors (FcR)</p> Signup and view all the answers

    Which immunoglobulin subclasses can activate the complement system in humans?

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

    What is the protein fragment produced as an important byproduct of the complement activation pathway?

    <p>C3b</p> Signup and view all the answers

    What allows erythrocytes to deliver antigen-antibody complexes to the liver or spleen for removal?

    <p>Binding of antigen-antibody complexes by C3b receptors</p> Signup and view all the answers

    Which cell type can direct the cytotoxic activities against target cells in antibody-dependent cell-mediated cytotoxicity (ADCC)?

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

    What is the role of the antibody in antibody-dependent cell-mediated cytotoxicity (ADCC)?

    <p>Acts as a newly acquired receptor enabling the attacking cell to recognize and kill the target cell</p> Signup and view all the answers

    What type of cells have Fc receptors that can link with antibody bound to target cells in antibody-dependent cell-mediated cytotoxicity (ADCC)?

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

    Which process is responsible for the movement of immunoglobulin across epithelial layers?

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

    Which antibody species is the major one that undergoes transcytosis in humans and mice?

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

    What type of transcytosis is a form of passive immunization?

    <p>Transcytosis of IgG from mother to fetus</p> Signup and view all the answers

    What is the main function of Fc receptors (FcR) in relation to antibodies?

    <p>Facilitate the movement of antibodies across cell membranes and transfer of IgG from mother to fetus</p> Signup and view all the answers

    Which cell types can passively acquire antibodies through Fc receptors?

    <p>B and T lymphocytes, neutrophils, mast cells, eosinophils, macrophages, natural killer cells</p> Signup and view all the answers

    What is the specific affinity of Fc receptors (FcR) in relation to the antibody molecule?

    <p>Affinity for the Fc portion of the antibody molecule</p> Signup and view all the answers

    Which IgG subclass readily crosses the placenta and plays a role in protecting the developing fetus?

    <p>IgG1</p> Signup and view all the answers

    Which IgG subclass is the most effective complement activator?

    <p>IgG3</p> Signup and view all the answers

    Which IgG subclass binds with high affinity to Fc receptors on phagocytic cells and mediates opsonization?

    <p>IgG1</p> Signup and view all the answers

    Is IgG the most abundant class in serum, constituting about 80% of the total serum immunoglobulin?

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

    Do IgG1, IgG3, and IgG4 readily cross the placenta and play an important role in protecting the developing fetus?

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

    Is IgG4 able to activate complement at all?

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

    Is IgM the first immunoglobulin class produced in a primary response to an antigen?

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

    Does IgM have a higher valency than the other isotypes due to its pentameric structure with 10 antigen-binding sites?

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

    Is IgM the first immunoglobulin to be synthesized by the neonate?

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

    Is IgM more efficient than IgG at activating complement?

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

    Is IgM found in very low concentrations in the intercellular tissue fluids due to its large size?

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

    Does IgM require less IgM than IgG to neutralize viral infectivity?

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

    Where is Immunoglobulin A (IgA) predominantly found?

    <p>Breast milk, saliva, tears, and mucus of the bronchial, genitourinary, and digestive tracts</p> Signup and view all the answers

    What is the daily production of secretory IgA compared to other immunoglobulin classes?

    <p>Greater than any other immunoglobulin class</p> Signup and view all the answers

    Where are IgA-secreting plasma cells concentrated?

    <p>Along mucous membrane surfaces</p> Signup and view all the answers

    What prevents the attachment of pathogens to mucosal cells?

    <p>Secretory IgA binding to surface antigens</p> Signup and view all the answers

    What does breast milk contain that helps protect newborns against infection?

    <p>Secretory IgA</p> Signup and view all the answers

    Which molecule in breast milk plays a key role in protecting newborns against infection?

    <p>Secretory IgA</p> Signup and view all the answers

    What is the role of the J chain in secretory IgA?

    <p>Linking at least two IgA molecules together</p> Signup and view all the answers

    Where does secretory IgA serve an important effector function?

    <p>Mucous membrane surfaces</p> Signup and view all the answers

    What plays an important role in maintaining the health of newborns due to the incomplete immune system of infants?

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

    What is the main function of IgE antibodies?

    <p>Mediate immediate hypersensitivity reactions</p> Signup and view all the answers

    Where does IgE bind in the body?

    <p>Fc receptors on blood basophils and tissue mast cells</p> Signup and view all the answers

    What was the basis for the first biological assay for IgE activity?

    <p>P-K reaction</p> Signup and view all the answers

    What is the main function of IgE antibodies?

    <p>Mediate immediate hypersensitivity reactions</p> Signup and view all the answers

    What does IgE bind to in the body?

    <p>Fc receptors on blood basophils and tissue mast cells</p> Signup and view all the answers

    What was the basis for the first biological assay for IgE activity?

    <p>P-K reaction (Prausnitz and Kustner reaction)</p> Signup and view all the answers

    Is allergen cross-linkage of receptor-bound IgE on mast cells responsible for causing release of substances that mediate allergic manifestations?

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

    Does degranulation of mast cells release substances that mediate allergic manifestations?

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

    Is the release of substances (blue dots) from mast cells responsible for mediating allergic manifestations?

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

    What was the basis for the discovery of Immunoglobulin D (IgD)?

    <p>Failure to react with anti-isotype antisera against known isotypes</p> Signup and view all the answers

    Which immunoglobulin is expressed as a major membrane-bound form by mature B cells?

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

    What is the current status of the role of IgD in the physiology of B cells?

    <p>Under investigation</p> Signup and view all the answers

    Which of the following is a member of the immunoglobulin superfamily?

    <p>Poly-Ig receptor</p> Signup and view all the answers

    Which protein is associated with class I MHC molecules?

    <p>β2-microglobulin</p> Signup and view all the answers

    Which of the following is a T-cell accessory protein?

    <p>CD28</p> Signup and view all the answers

    What is the composition of the B-cell receptor (BCR)?

    <p>Membrane-bound immunoglobulin (mIg) and disulfide-linked heterodimers called Ig- α /Ig-β</p> Signup and view all the answers

    What is the length of the cytoplasmic tail in the Ig- α chain of the B-cell receptor (BCR)?

    <p>61 amino acids</p> Signup and view all the answers

    What is the function of the cytoplasmic tails in both Ig- α and Ig- β chains?

    <p>Interact with intracellular signaling molecules</p> Signup and view all the answers

    What are the three major categories of antigenic determinants on immunoglobulin molecules?

    <p>Isotypic determinants, Allotypic determinants, Idiotypic determinants</p> Signup and view all the answers

    Where are the idiotypic determinants located in the antibody molecule?

    <p>Characteristic portions of the antibody molecule</p> Signup and view all the answers

    What are the three major categories of antigenic determinants on immunoglobulin molecules?

    <p>Isotypic determinants, Allotypic determinants, Idiotypic determinants</p> Signup and view all the answers

    What collectively defines each heavy-chain class and subclass and each light-chain type and subtype within a species?

    <p>Isotypic determinants</p> Signup and view all the answers

    What will be recognized as foreign when an antibody from one species is injected into another species?

    <p>Isotypic determinants</p> Signup and view all the answers

    What are encoded by separate constant region genes, with all members of a species carrying the same constant-region genes?

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

    What are allotypic determinants?

    <p>Subtle amino acid differences encoded by multiple alleles for some genes</p> Signup and view all the answers

    When can antibodies to allotypic determinants be produced in response to paternal allotypic determinants?

    <p>During pregnancy</p> Signup and view all the answers

    What can give rise to antibodies to allotypic determinants?

    <p>Pregnancy and blood transfusion</p> Signup and view all the answers

    Where are idiotope sequences located?

    <p>Both in the antigen-binding site and outside of it</p> Signup and view all the answers

    What is each individual antigenic determinant of the variable region referred to as?

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

    In which region may an idiotope comprise variable-region sequences outside of the antigen-binding site?

    <p>Framework region</p> Signup and view all the answers

    What type of differences occur in the constant region from one species to another when it comes to immunoglobulins?

    <p>Isotypic differences</p> Signup and view all the answers

    Which type of differences occur in the variable regions and can differ even on antibodies of the same isotype?

    <p>Idiotypic differences</p> Signup and view all the answers

    What term is used for the differences (alleles) that occur in some individuals with respect to immunoglobulins?

    <p>Allotypic differences</p> Signup and view all the answers

    What type of antibodies are derived from a single clone and specific for a single epitope?

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

    What is the advantage of a polyclonal antibody response for an organism in vivo?

    <p>Facilitates localization, phagocytosis, and complement-mediated lysis of antigen</p> Signup and view all the answers

    What is the primary function of monoclonal antibodies?

    <p>Research, diagnostic, and therapeutic purposes</p> Signup and view all the answers

    What is a hybridoma?

    <p>A hybrid cell resulting from the fusion of a B cell and a myeloma cell</p> Signup and view all the answers

    What are the properties of hybridoma cells?

    <p>They possess immortal-growth properties and secrete large quantities of monoclonal antibody</p> Signup and view all the answers

    Why was the work by Kohler and Milstein significant?

    <p>It provided immunologists with a powerful and versatile research tool</p> Signup and view all the answers

    Why are monoclonal antibodies useful in clinical applications?

    <p>They are highly specific and uniform</p> Signup and view all the answers

    What are the clinical uses of monoclonal antibodies?

    <p>Diagnostic reagents (e.g. cancer metastasis)</p> Signup and view all the answers

    What is a key advantage of monoclonal antibodies in terms of production?

    <p>They can be produced in large quantities</p> Signup and view all the answers

    What is the target of adalimumab (Humira)?

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

    Which cell type is targeted by rituximab (Rituxan)?

    <p>Lymphomal B cells</p> Signup and view all the answers

    What is the term for human monoclonal antibodies drugs, indicated by the suffix (-umab)?

    <p>Monoclonal antibodies drugs</p> Signup and view all the answers

    Monoclonal antibodies drugs can be indicated by the suffix (-umab)?

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

    Adalimumab, known as Humira, targets TNF to reduce inflammation?

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

    Rituximab, known as Rituxan, targets CD20 found on lymphomal B cells?

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

    Study Notes

    Antibodies and the Immune Response

    • Antibodies, or immunoglobulins, are specialized proteins produced by B cells in response to antigens.
    • The immune system recognizes complex antigens through B cell receptors, leading to the activation of B cells.
    • B cells differentiate into plasma cells, which produce antibodies specifically targeting these antigens.

    Structure and Composition of Antibodies

    • Antibodies typically consist of four peptide chains, including two heavy chains and two light chains.
    • Each light chain is linked to a heavy chain via disulfide bonds, contributing to a stable structure.
    • The antigen-binding site comprises variable regions of both heavy and light chains, allowing specific binding to antigens.
    • Heavy chains determine the antibody's class and subclass, with specific constant regions.

    Biological Functions of Antibodies

    • The constant region of antibodies mediates most biological functions and interacts with other immune components.
    • Smaller antigens fit into the variable regions, while larger antigens engage via multiple interaction sites.

    Antibody Types and Their Functions

    • IgG is the most abundant antibody in serum, constituting about 80% and is crucial for opsonization and neutralization.
    • IgM is produced first in responses to antigens, characterized by its pentameric structure allowing high valency (10 binding sites).
    • IgA is primarily found in mucosal areas and secretions, providing barrier protection against pathogens.

    Roles of IgE and IgD

    • IgE is involved in allergic reactions; it binds to allergens and activates mast cells upon cross-linkage.
    • IgD is present on the surface of B cells and plays a less-defined role in B cell physiology.

    Antibody Subtypes and Clinical Applications

    • Humans have multiple IgG subclasses (IgG1, IgG2, IgG3, IgG4) that differ in their ability to activate complement and cross the placenta.
    • Monoclonal antibodies are derived from a single clone and are highly specific for one epitope, useful for targeted therapies.

    Mechanisms of Antibody Function

    • Antibodies can opsonize pathogens, enhancing their recognition and phagocytosis by immune cells.
    • Fc receptors on phagocytic cells facilitate the recognition of antibody-coated targets, leading to destruction via ADCC.

    Transcytosis and Passive Immunization

    • Transcytosis is the process by which antibodies cross epithelial layers; secretory IgA is a primary species involved.
    • Passive immunization occurs when maternal antibodies, particularly IgG, are transmitted to offspring, providing early immunity.

    Antibody Diversity and Recognition

    • Antibodies exhibit variability, classified into idiotypic and allotypic determinants; idiotypes vary within an individual whereas allotypes vary among individuals of the same species.
    • Hybridoma technology enables the production of monoclonal antibodies, combining the specificity of antibodies with the proliferation ability of myeloma cells.
    • The terms "B-cell receptor (BCR)" and "immunoglobulin superfamily" refer to components integral to the adaptive immune response.
    • Class I MHC molecules are associated with the recognition of foreign antigens by T cells.

    Key Points on Immune Function

    • The signal-transduction pathway initiated by the engagement of antibodies on cell surfaces leads to various immune responses, including phagocytosis.
    • The different classes of immunoglobulins are crucial in providing a tailored immune response to diverse pathogens, ensuring overall immune defense.

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    Test your knowledge about the diversity and specificity of antibodies, including their production by B cells and the binding to antigenic determinants. Learn about the complex immune response and the generation of monoclonal antibodies.

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