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18.E: Specific Adaptive Host Defenses (Exercises)

  • Page ID
    78117
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    18.1: Architecture of the Immune System

    Adaptive immunity is defined by two important characteristics: specificity and memory. Specificity refers to the adaptive immune system’s ability to target specific pathogens, and memory refers to its ability to quickly respond to pathogens to which it has previously been exposed. For example, when an individual recovers from chickenpox, the body develops a memory of the infection that will specifically protect it from the causative agent if it is exposed to the virus again later.

    Multiple Choice

    Antibodies are produced by ________.

    1. plasma cells
    2. T cells
    3. bone marrow
    4. B cells
    Answer

    A

    Cellular adaptive immunity is carried out by ________.

    1. B cells
    2. T cells
    3. bone marrow
    4. neutrophils
    Answer

    B

    A single antigen molecule may be composed of many individual ________.

    1. T-cell receptors
    2. B-cell receptors
    3. MHC II
    4. epitopes
    Answer

    D

    Which class of molecules is the most antigenic?

    1. polysaccharides
    2. lipids
    3. proteins
    4. carbohydrates
    Answer

    C

    Matching

    Match the antibody class with its description.

    ___IgA A. This class of antibody is the only one that can cross the placenta.
    ___IgD B. This class of antibody is the first to appear after activation of B cells.
    ___IgE C. This class of antibody is involved in the defense against parasitic infections and involved in allergic responses.
    ___IgG D. This class of antibody is found in very large amounts in mucus secretions.
    ___IgM E. This class of antibody is not secreted by B cells but is expressed on the surface of naïve B cells.
    Answer

    d, e, c, a, b

    Fill in the Blank

    There are two critically important aspects of adaptive immunity. The first is specificity, while the second is ________.

    Answer

    memory

    ________ immunity involves the production of antibody molecules that bind to specific antigens.

    Answer

    Humoral

    The heavy chains of an antibody molecule contain ________ region segments, which help to determine its class or isotype.

    Answer

    constant

    The variable regions of the heavy and light chains form the ________ sites of an antibody.

    Answer

    antigen-binding

    Short Answer

    What is the difference between humoral and cellular adaptive immunity?

    What is the difference between an antigen and a hapten?

    Describe the mechanism of antibody-dependent cell-mediated cytotoxicity.

    18.2: Antigens, Antigen Presenting Cells, and Major Histocompatibility Complexes

    Major histocompatibility complex (MHC) molecules are expressed on the surface of healthy cells, identifying them as normal and “self” to natural killer (NK) cells. MHC molecules also play an important role in the presentation of foreign antigens, which is a critical step in the activation of T cells and thus an important mechanism of the adaptive immune system.

    Multiple Choice

    MHC I molecules present

    1. processed foreign antigens from proteasomes.
    2. processed self-antigens from phagolysosome.
    3. antibodies.
    4. T cell antigens.
    Answer

    A

    MHC II molecules present

    1. processed self-antigens from proteasomes.
    2. processed foreign antigens from phagolysosomes.
    3. antibodies.
    4. T cell receptors.
    Answer

    B

    Which type of antigen-presenting molecule is found on all nucleated cells?

    1. MHC II
    2. MHC I
    3. antibodies
    4. B-cell receptors
    Answer

    B

    Which type of antigen-presenting molecule is found only on macrophages, dendritic cells, and B cells?

    1. MHC I
    2. MHC II
    3. T-cell receptors
    4. B-cell receptors
    Answer

    B

    Fill in the Blank

    MHC molecules are used for antigen ________ to T cells.

    Answer

    presentation

    MHC II molecules are made up of two subunits (α and β) of approximately equal size, whereas MHC I molecules consist of a larger α subunit and a smaller subunit called ________.

    Answer

    β2 microglobulin

    Critical Thinking

    Which mechanism of antigen presentation would be used to present antigens from a cell infected with a virus?

    Which pathway of antigen presentation would be used to present antigens from an extracellular bacterial infection?

    18.3: T Lymphocytes

    The antibodies involved in humoral immunity often bind pathogens and toxins before they can attach to and invade host cells. Thus, humoral immunity is primarily concerned with fighting pathogens in extracellular spaces. However, pathogens that have already gained entry to host cells are largely protected from the humoral antibody-mediated defenses. Cellular immunity, on the other hand, targets and eliminates intracellular pathogens through the actions of T lymphocytes, or T cells.

    Multiple Choice

    What is a superantigen?

    1. a protein that is highly efficient at stimulating a single type of productive and specific T cell response
    2. a protein produced by antigen-presenting cells to enhance their presentation capabilities
    3. a protein produced by T cells as a way of increasing the antigen activation they receive from antigen-presenting cells
    4. a protein that activates T cells in a nonspecific and uncontrolled manner
    Answer

    D

    To what does the TCR of a helper T cell bind?

    1. antigens presented with MHC I molecules
    2. antigens presented with MHC II molecules
    3. free antigen in a soluble form
    4. haptens only
    Answer

    B

    Cytotoxic T cells will bind with their TCR to which of the following?

    1. antigens presented with MHC I molecules
    2. antigens presented with MHC II molecules
    3. free antigen in a soluble form
    4. haptens only
    Answer

    A

    A ________ molecule is a glycoprotein used to identify and distinguish white blood cells.

    1. T-cell receptor
    2. B-cell receptor
    3. MHC I
    4. cluster of differentiation
    Answer

    D

    Name the T helper cell subset involved in antibody production.

    1. TH1
    2. TH2
    3. TH17
    4. CTL
    Answer

    B

    Fill in the Blank

    A ________ T cell will become activated by presentation of foreign antigen associated with an MHC I molecule.

    Answer

    cytotoxic

    A ________ T cell will become activated by presentation of foreign antigen in association with an MHC II molecule.

    Answer

    helper

    A TCR is a protein dimer embedded in the plasma membrane of a T cell. The ________ region of each of the two protein chains is what gives it the capability to bind to a presented antigen.

    Answer

    variable

    Peripheral tolerance mechanisms function on T cells after they mature and exit the ________.

    Answer

    thymus

    Both ________ and effector T cells are produced during differentiation of activated T cells.

    Answer

    memory

    Short Answer

    What is the basic difference in effector function between helper and cytotoxic T cells?

    What necessary interactions are required for activation of helper T cells and activation/effector function of cytotoxic T cells?

    18.4: B Lymphocytes and Antibodies

    Humoral immunity refers to mechanisms of the adaptive immune defenses that are mediated by antibodies secreted by B lymphocytes, or B cells. This section focuses on B cells and discusses their production and maturation, receptors, and mechanisms of activation.

    Multiple Choice

    Which of the following would be a T-dependent antigen?

    1. lipopolysaccharide
    2. glycolipid
    3. protein
    4. carbohydrate
    Answer

    C

    Which of the following would be a BCR?

    1. CD4
    2. MHC II
    3. MHC I
    4. IgD
    Answer

    D

    Which of the following does not occur during the lag period of the primary antibody response?

    1. activation of helper T cells
    2. class switching to IgG
    3. presentation of antigen with MHC II
    4. binding of antigen to BCRs
    Answer

    B

    Fill in the Blank

    ________ antigens can stimulate B cells to become activated but require cytokine assistance delivered by helper T cells.

    Answer

    T-dependent

    T-independent antigens can stimulate B cells to become activated and secrete antibodies without assistance from helper T cells. These antigens possess ________ antigenic epitopes that cross-link BCRs.

    Answer

    repetitive

    Critical Thinking

    A patient lacks the ability to make functioning T cells because of a genetic disorder. Would this patient’s B cells be able to produce antibodies in response to an infection? Explain your answer.

    18.5: Vaccines

    By artificially stimulating the adaptive immune defenses, a vaccine triggers memory cell production similar to that which would occur during a primary response. In so doing, the patient is able to mount a strong secondary response upon exposure to the pathogen—but without having to first suffer through an initial infection. In this section, we explore several different kinds of artificial immunity along with various types of vaccines and their mechanisms for inducing artificial immunity.

    Multiple Choice

    A patient is bitten by a dog with confirmed rabies infection. After treating the bite wound, the physician injects the patient with antibodies that are specific for the rabies virus to prevent the development of an active infection. This is an example of:

    1. Natural active immunity
    2. Artificial active immunity
    3. Natural passive immunity
    4. Artificial passive immunity
    Answer

    D

    A patient gets a cold, and recovers a few days later. The patient's classmates come down with the same cold roughly a week later, but the original patient does not get the same cold again. This is an example of:

    1. Natural active immunity
    2. Artificial active immunity
    3. Natural passive immunity
    4. Artificial passive immunity
    Answer

    A

    Matching

    Match each type of vaccine with the corresponding example.

    ___inactivated vaccine A. Weakened influenza virions that can only replicate in the slightly lower temperatures of the nasal passages are sprayed into the nose. They do not cause serious flu symptoms, but still produce an active infection that induces a protective adaptive immune response.
    ___live attenuated vaccine B. Tetanus toxin molecules are harvested and chemically treated to render them harmless. They are then injected into a patient’s arm.
    ___toxoid vaccine C. Influenza virus particles grown in chicken eggs are harvested and chemically treated to render them noninfectious. These immunogenic particles are then purified and packaged and administered as an injection.
    ___subunit vaccine D. The gene for hepatitis B virus surface antigen is inserted into a yeast genome. The modified yeast is grown and the virus protein is produced, harvested, purified, and used in a vaccine.
    Answer

    C, A, B, D

    Fill in the Blank

    A(n) ________ pathogen is in a weakened state; it is still capable of stimulating an immune response but does not cause a disease.

    Answer

    attenuated

    ________ immunity occurs when antibodies from one individual are harvested and given to another to protect against disease or treat active disease.

    Answer

    Artificial passive

    In the practice of ________, scabs from smallpox victims were used to immunize susceptible individuals against smallpox.

    Answer

    variolation

    Short answer

    Briefly compare the pros and cons of inactivated versus live attenuated vaccines.


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