Immunology: Innate and Adaptive Immunity
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Questions and Answers

What is the main characteristic of T-independent antigens?

  • They have repeating epitopes that can cross-link B cell receptors. (correct)
  • They only target a specific type of antibody.
  • They stimulate the B cells to produce memory cells.
  • They require help from T helper cells to activate B cells.

    • How does the human immune system achieve a diversity of antibodies?

  • Via a fixed number of genetic sequences that are randomly activated.
  • Through the splicing of multiple gene segments before exposure to antigens. (correct)
  • By clonal expansion of specific B cells upon encountering an antigen.
  • By using a large number of genes that code for unique antibodies.

    • What is clonal deletion in the context of B cell development?

  • The elimination of potentially harmful B cells in the bone marrow. (correct)
  • The process by which B cells are activated by T helper cells.
  • The stimulation of B cells by T-independent antigens.
  • The production of varying antibody types to increase immune response.

    • What determines the affinity of an antibody for an antigen?

    <p>The strength of the bond between the epitope and the antibody's binding site.</p> Signup and view all the answers

    What is a feature of the immunoglobulin genes related to antibody diversity?

    <p>They consist of segments that can rearrange to generate diversity.</p> Signup and view all the answers

    What is the primary function of adaptive immunity?

    <p>To recognize and target specific pathogens after exposure</p> Signup and view all the answers

    Which statement accurately describes the role of innate immunity?

    <p>It acts rapidly and non-specifically against pathogens.</p> Signup and view all the answers

    What consequence may arise if the immune system fails to distinguish 'self' from 'non-self'?

    <p>Possibility of autoimmune diseases</p> Signup and view all the answers

    How does vaccination contribute to the adaptive immune system?

    <p>It uses a harmless version of a pathogen to trigger an adaptive response.</p> Signup and view all the answers

    What is an important feature of the adaptive immune response?

    <p>It generates memory cells for long-lasting immunity.</p> Signup and view all the answers

    In what scenario is the adaptive immune system activated?

    <p>When innate defenses are insufficient to stop a microbe</p> Signup and view all the answers

    What aspect of adaptive immunity is critical for its long-term effectiveness?

    <p>The presence of memory cells that recall previous infections</p> Signup and view all the answers

    What is the primary role of IgG antibodies in relation to the fetus?

    <p>They cross the placenta to provide immunity.</p> Signup and view all the answers

    What term describes the process where antibodies cause cells to clump together?

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

    Which statement accurately describes the structure of IgG antibodies?

    <p>They are Y-shaped monomers.</p> Signup and view all the answers

    Which of the following is NOT a function of IgG antibodies?

    <p>Inducing apoptosis in target cells.</p> Signup and view all the answers

    How do IgG antibodies facilitate the process of phagocytosis?

    <p>By binding to antigens and enhancing opsonization.</p> Signup and view all the answers

    What percentage of serum antibodies does IgG constitute in a healthy individual?

    <p>80%</p> Signup and view all the answers

    Which characteristic differentiates IgG from other immunoglobulin classes?

    <p>Its ability to cross the placenta.</p> Signup and view all the answers

    Which immune process allows IgG to enter tissue fluids from the blood?

    <p>Diffusion through blood vessel walls.</p> Signup and view all the answers

    What triggers the activation of the complement system when IgG is bound to an antigen?

    <p>The constant region of IgG.</p> Signup and view all the answers

    In what primary area of the body do IgG antibodies exert their functions?

    <p>Blood and lymphatic system</p> Signup and view all the answers

    What is the primary function of Fc regions in antibodies?

    <p>They interact with complement proteins to activate the complement system.</p> Signup and view all the answers

    Which immunoglobulin class is secreted only as a pentamer?

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

    How do macrophages enhance their ability to eliminate targets?

    <p>Through the presence of Fc receptors on their surface.</p> Signup and view all the answers

    Which statement accurately describes the structure of an antibody?

    <p>It consists of two light chains and two heavy chains linked by disulfide bridges.</p> Signup and view all the answers

    In the process of generating antibody diversity, what is spliced together with the variable region?

    <p>A gene corresponding to the appropriate constant region.</p> Signup and view all the answers

    What is the main role of the variable regions in an antibody?

    <p>To recognize and bind specific antigens.</p> Signup and view all the answers

    What distinguishes IgA from other immunoglobulin classes?

    <p>It can be present as either a monomer or a dimer.</p> Signup and view all the answers

    Which immune response does the classical pathway of the complement system primarily activate?

    <p>Phagocytosis triggered by antibody-antigen complexes.</p> Signup and view all the answers

    What feature of IgG, IgD, and IgE distinguishes them in terms of structure?

    <p>They are secreted exclusively as monomers.</p> Signup and view all the answers

    What initiates the internalization of an antigen by B cells?

    <p>Binding of IgM to the antigen</p> Signup and view all the answers

    How does the B cell present the processed antigen to T helper cells?

    <p>By displaying fragments on MHC class II molecules</p> Signup and view all the answers

    What role do T helper cells play in the activation of B cells?

    <p>They release cytokines to promote B cell expansion</p> Signup and view all the answers

    What is the final cell type that B cells can differentiate into following activation?

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

    What is the function of the IgM antibody in B cell activation?

    <p>It serves as a receptor to bind the antigen</p> Signup and view all the answers

    What is required for the clonal expansion of a B cell after activation?

    <p>Cytokines from activated T helper cells</p> Signup and view all the answers

    What kind of cell receptor recognizes the antigen presented by B cells on MHC class II?

    <p>T cell receptor (TCR)</p> Signup and view all the answers

    What happens to the antigen after it has been internalized by a B cell?

    <p>It is broken down and displayed on MHC-2 molecules.</p> Signup and view all the answers

    Which of the following describes the role of cytokines in the immune response?

    <p>They signal for cell recruitment and proliferation.</p> Signup and view all the answers

    What component of B cells interacts specifically with the antigen?

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

    Study Notes

    Innate Immunity

    • Responds nonspecifically to pathogens
    • Has no memory
    • Works with adaptive immunity
    • Includes physical barriers (skin, mucous membranes)

    Adaptive Immunity

    • Specific responses to pathogens
    • Recognizes "self" from "nonself"
    • Activated when innate defenses fail
    • Acquired through infection or vaccination
    • Provides memory

    Adaptive Immune System Components

    • Humoral immunity (B cells):
      • Recognizes antigens outside cells
      • Produces antibodies
    • Cellular immunity (T cells):
      • Recognizes antigens inside cells
      • Destroys infected cells

    Cells of the Adaptive Immune System

    • Originate from pluripotent stem cells in bone marrow or fetal liver
    • Mature in different locations (B cells in bone marrow, T cells in thymus)
    • Found primarily in blood and lymphoid organs

    Humoral Immunity

    • Involves B cells
    • Involves B-cell receptors (BCRs)
    • Activated B cells produce antibodies
    • Antibodies bind to antigens on pathogens and target pathogens for destruction
    • Antibodies cross the blood and tissue fluids
    • Antibodies can be part of a response faster

    Cellular Immunity

    • Involves T cells
    • Involves T-cell receptors (TCRs)
    • T cells recognize antigens presented by antigen-presenting cells (APCs).
    • T helper cells (TH) help activate B cells and other immune cells.
    • Cytotoxic T cells (Tc) directly kill infected cells.
      • T regulatory cells (Treg) help regulate the immune response.

    Cytokines

    • Chemical messengers between immune cells
    • Initiate inflammatory responses
    • Act as attractants for certain immune cells
    • Influence the proliferation and differentiation of various immune cells

    Antigens

    • Substances that elicit immune responses
    • Usually proteins or large polysaccharides
    • Components of invading microbes or foreign substances
    • Can be parts of a capsule, cells, or other structures
    • Can be lipids, or nucleic acids

    Antibodies

    • Proteins produced by plasma cells (activated B cells)
    • Bind specifically to antigens
    • Have a variable (V) region and constant (C) region
    • Variable regions bind to specific antigens
    • Valence refers to the number of antigen-binding sites on an antibody
    • Antibodies are capable of neutralizing foreign substances directly/initiating a response to kill the pathogen

    Immune System Cells

    • B cells are responsible for humoral immunity
    • T cells, like cytotoxic or helper cells, are for cellular immunity
    • Macrophages, dendritic, and B cells are Antigen Presenting Cells.

    Immunological Memory

    • Adaptive immunity has a memory component
    • Memory cells are produced following an initial infection
    • Memory cells provide a faster and more effective response to a subsequent exposure to the same pathogen.

    Response Types

    • Primary response (first exposure): Takes time, includes signs and symptoms of the disease (4-7 days)
    • Secondary response (repeated exposure): Faster, more effective response due to memory cells

    Antibody Classes

    • IgG
    • IgM
    • IgA
    • IgD
    • IgE
      • Each class of antibody has a specific structure and function.

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    Lecture 21: Adaptive Immunity PDF

    Description

    This quiz explores the key concepts of innate and adaptive immunity, focusing on their roles, components, and functions in the immune response. Understand how the immune system differentiates between pathogens and self, and learn about the crucial cells involved in humoral and cellular responses.

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