Basic Immunology 5th Edition Abbas Test Bank Abbas: Basic Immunology, 5th Edition Chapter 01: Introduction to the Immune System Test Bank MULTIPLE CHOICE 1. The principal function of the immune system is: A. Defense against cancer B. Repair of injured tissues C. Defense against microbial infections D. Prevention of inflammatory diseases E. Protection against environmental toxins ANS: C The immune system has evolved in the setting of selective pressures imposed by microbial infections. Although immune responses to cancer may occur, the concept that “immunosurveillance” against cancer is a principal function of the immune system is controversial. Repair of injured tissues may be a secondary consequence of the immune responses and inflammation. Although the immune system has regulatory features that are needed to prevent excessive inflammation, prevention of inflammatory diseases is not a primary function. The immune system can protect against microbial toxins, but it generally does not offer protection against toxins of nonbiolN ogUicRoSriI giN n.GTB.COM 2. Which of the following infectious diseases was prevented by the first successful vaccination? A. Polio B. Tuberculosis C. Smallpox D. Tetanus E. Rubella ANS: C In 1798, Edward Jenner reported the first intentional successful vaccination, which was against smallpox in a boy, using material from the cowpox pustules of a milkmaid. In 1980, smallpox was reported to be eradicated worldwide by a vaccination program. Effective vaccines against tetanus toxin, rubella virus, and poliovirus were developed in the 20th century and are widely used. There is no effective vaccine against Mycobacterium tuberculosis. 3. A previously healthy 8-year-old boy is infected with an upper respiratory tract virus for the first time. During the first few hours of infection, which one of the following events occurs? A. The adaptive immune system responds rapidly to the virus and keeps the viral infection under control. B. The innate immune system responds rapidly to the viral infection and keeps the viral infection under control. C. Passive immunity mediated by maternal antibodies limits the spread of infection. D. B and T lymphocytes recognize the virus and stimulate the innate immune response.
E. The virus causes malignant transformation of respiratory mucosal epithelial cells, and the malignant cells are recognized by the adaptive immune system. ANS: B The innate immune response to microbes develops within hours of infection, well before the adaptive immune response. B and T lymphocytes are components of the adaptive immune response, and they would not be able to respond to a newly encountered virus before the innate immune response. An 8-year-old boy would no longer have maternal antibodies from transplacental passive transfer and is unlikely to be breast-feeding, which is another potential source of maternal antibodies. Malignant transformation takes months or years to develop. 4. Which of the following is a unique property of the adaptive immune system? A. Highly diverse repertoire of specificities for antigens B. Self-nonself discrimination C. Recognition of microbial structures by both cell-associated and soluble receptors D. Protection against viral infections E. Responses that have the same kinetics and magnitude on repeated exposure to the same microbe ANS: A Highly diverse repertoires of specificities for antigens are found only in T and B lymphocytes, which are the central cellular components of the adaptive immune system. Both the innate and the adaptive immune systems use cell-associated and soluble receptors to recognize microbes, display some degree of self-nonself discrimination, and protect against viruses. On repeated exposure to the same microbe, the aN dU apR tiS veIim mT unB e. reC spOoM nse becomes more rapid and of greater NG magnitude; this is the manifestation of memory. 5. Antibodies and T lymphocytes are the respective mediators of which two types of immunity? A. Innate and adaptive B. Passive and active C. Specific and nonspecific D. Humoral and cell-mediated E. Adult and neonatal ANS: D Both B and T lymphocytes are principal components of adaptive immunity. B lymphocytes produce antibodies, which are the recognition and effector molecules of humoral immune responses to extracellular pathogens. T cells recognize and promote eradication of intracellular pathogens in cell-mediated immunity. Passive and active immunity both can be mediated by either B or T lymphocytes. Specific immunity is another term for adaptive immunity. Both B and T lymphocytes participate in adult adaptive immunity but are still developing in the neonatal period. 6. A standard treatment of animal bite victims, when there is a possibility that the animal was infected with the rabies virus, is administration of human immunoglobulin preparations containing anti–rabies virus antibodies. Which type of immunity would be established by this treatment? A. Active humoral immunity
B. Passive humoral immunity C. Active cell-mediated immunity D. Passive cell-mediated immunity E. Innate immunity ANS: B Humoral immunity is mediated by antibodies. The transfer of protective antibodies made by one or more individuals into another individual is a form of passive humoral immunity. Active immunity to an infection develops when an individual’s own immune system responds to the microbe. Cell-mediated immunity is mediated by T lymphocytes, not antibodies, and innate immunity is not mediated by either antibodies or T lymphocytes. 7. At 15 months of age, a child received a measles-mumps-rubella vaccine (MMR). At age 22, she is living with a family in Mexico that has not been vaccinated and she is exposed to measles. Despite the exposure, she does not become infected. Which of the following properties of the adaptive immune system is best illustrated by this scenario? A. Specificity B. Diversity C. Specialization D. Memory E. Nonreactivity to self ANS: D Protection against infections after vaccination is due to immunologic memory of the adaptive immune system. Memory is manifeN stU edRaS sI am orT eB ra. piC dlO yM developing and vigorous response on NG repeat exposure to an antigen compared with the first exposure. Specificity and diversity are properties related to the range of antigenic structures recognized by the immune system, and specialization is the ability of the adaptive immune system to use distinct effector mechanisms for distinct infections. 8. A vaccine administered in the autumn of one year may protect against the prevalent strain of influenza virus that originated in Hong Kong that same year, but it will not protect against another strain of influenza virus that originated in Russia. This phenomenon illustrates which property of the adaptive immune system? A. Specificity B. Amnesia C. Specialization D. Cultural diversity E. Self-tolerance ANS: A Adaptive immune responses are highly specific for distinct molecular structures, which may be present in a vaccine and be produced by one strain of virus but not by a closely related strain. Amnesia, although generally not used in immunology, implies lack of memory, but the efficacy of the vaccine against the Hong Kong strain implies it has induced memory. The same effector mechanisms would be required to combat different strains of influenza, and therefore failure of a vaccine to protect against two different strains of virus is not related to specialization of effector functions.
9. The two major functional classes of effector T lymphocytes are: A. Helper T lymphocytes and cytotoxic T lymphocytes B. Natural killer cells and cytotoxic T lymphocytes C. Memory T cells and effector T cells D. Helper cells and antigen-presenting cells E. Cytotoxic T lymphocytes and target cells ANS: A T cells can be classified into effector subsets that perform different effector functions. Most effector T cells are either helper T lymphocytes, which promote macrophage and B cell responses to infections, or cytotoxic T lymphocytes, which directly kill infected cells. Natural killer cells are not T lymphocytes. Antigen-presenting cells usually are not T cells. Memory T cells are not effector T cells. 10. Which of the following cell types is required for all humoral immune responses? A. Natural killer cells B. Dendritic cells C. Cytolytic T lymphocytes D. B lymphocytes E. Helper T lymphocytes ANS: D Humoral immune responses are antibody-mediated immune responses, and all antibodies are made by B lymphocytes and by no N otU heR rS ceI llNtyGpT e.B.COM 11. During a humoral immune response to a newly encountered bacterial infection, B cells are first stimulated to proliferate and then secrete antibodies specific for the bacterium. The antibodies may then bind to the bacteria and facilitate ingestion of the microbes by phagocytic cells. In what phase of the humoral immune response does the binding of secreted antibodies to bacteria occur? A. Recognition phase B. Activation phase C. Effector phase D. Homeostatic phase E. Memory phase ANS: C The effector phase of an immune response occurs when cells or molecules eliminate the microbe or microbial toxin. In a humoral immune response, the effector phase includes secretion of antibody, binding of the antibody to the microbe or toxin, and subsequent antibody-dependent elimination of the microbe or toxin. The recognition phase is the initial binding of the antigen by the naive lymphocyte. The activation phase includes proliferation and differentiation of lymphocytes in response to antigen recognition. The homeostatic phase follows the effector phase, during which the response wanes. In the memory phase, memory B cells and antibodies secreted by long-lived antibody-secreting cells are “waiting” for a repeat exposure to the microbe.
Basic Immunology 5th Edition Abbas Test Bank Test Bank
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A. Btk B. Itk C. Tec D. PI-3 kinase E. Zap-70 ANS: A Btk is a Tec family protein tyrosine kinase that is particularly important in pre-B cell receptor complex signaling, and therefore in B cell maturation and activation. Mutations in Btk are responsible for X-linked agammaglobulinemia. Itk and Tec are other members of the Tec family that are important in T cells. PI-3 kinase is a phospholipid kinase involved in signaling in many cell types, including B and T cells, and Zap-70 is a protein tyrosine kinase particularly important in TCR signaling in T cells. 12. All of the following are early T cell events that occur after antigen recognition by the TCR EXCEPT: A. Formation of the immunologic synapse B. Recruitment of signaling molecules, such as LAT, to glycolipid-enriched domains known as lipid rafts C. Enhanced adhesion between T cells and antigen-presenting cells (APCs) via T cell integrin LFA-1 and its ligand on the APC, ICAM-1, at the central zone of the immunologic synapse D. Clustering of the TCR and coreceptors leading to phosphorylation of ITAMs on CD3 by Lck E. Binding of CD28 with costiN mU ulR atS orI sN onGA inOthMe cSMAC, resulting in signal TPBC.s C transduction activation ANS: C On binding of the TCR complex with MHC-associated peptides on an antigen-presenting cell (APC), several T cell surface proteins and intracellular signaling molecules are rapidly mobilized to the site of contact, known as the immunologic synapse. Molecules that are recruited to the central supramolecular activation cluster, or center of the synapse, include the TCR complex (TCR, CD3, and chains), CD4 or CD8 coreceptors, and costimulatory molecules (CD28). The clustering of signaling molecules results in the phosphorylation of ITAMs on CD3 by CD4- or CD8-associated Lck. Integrins remain at the peripheral zone of the synapse and stabilize the binding of the T cell to the APC. LAT is a transmembrane adaptor molecule recruited to the synapse whose cytoplasmic tail forms part of a scaffold of signaling molecules. 13. An experiment is performed in which a point mutation is introduced randomly into the Zap70 gene for a particular strain of mice. The mutant mice display a defect in T cell development. However, precursor T cells isolated from the thymus of these mice show normal expression levels of Zap-70 of the correct molecular weight. On further in vitro analysis, the mutant Zap-70 is found to bind to ITAM motifs in the cytoplasmic tail of the chain, but only when the chain is phosphorylated. No phosphorylated LAT is detected, however. Given these data, in which of the following protein domains is the mutation most likely to be present? A. Pleckstrin homology (PH) domain B. Proline-rich (PR) domain C. SH1 domain
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Basic Immunology 5th Edition Abbas Test Bank Test Bank
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D. SH2 domain E. SH3 domain ANS: C In this experiment, the mutant Zap-70 can still bind to the phosphorylated chains but cannot phosphorylate LAT. This suggests that the SH2 domains are normal but that the SH1 kinase domain has been mutated. Zap-70 does not contain a PH, PR, or SH3 domain. The PH domain allows proteins to localize to the membrane by binding to PIP3. PR domains mediate proteinprotein interactions via binding to SH3 domains. 14. Which one of the following accurately depicts the correct order of events in a TCR signal transduction pathway? A. TCR → Lck → Zap-70 → LAT → Grb-2 → SOS → Ras → Erk → Fos B. TCR → Lck → Zap-70 → LAT → SOS → Grb-2 → Ras → Erk → Fos C. TCR → Lck → ITK → LAT → Grb-2 → SOS → Ras → Erk → Fos D. TCR → Lck → Zap-70 → LAT → SOS → Grb-2 → Ras → Erk → Jun E. TCR → Lck → Zap-70 → LAT → PLC → DAG → calcium release ANS: A Activated Zap-70 phosphorylates the transmembrane adapter protein LAT at tyrosine residues, which serve as docking sites for SH2 domains of other proteins. In one pathway, the SH2 domain of Grb-2 binds to phosphorylated LAT. Grb-2 is then able to recruit Sos to the membrane. Sos catalyzes GDP/GTP exchange on Ras, a G protein that is active when guanosine triphosphate (GTP) is bound and inactive when guanosine diphosphate (GDP) is bound. Active Ras functions as an allosteric activator of mitogenN -aU ctR ivS atI edNpGroTtB ein.kCiO naM ses (MAPK), leading to downstream activation of Erk through phosphorylation. Activated Erk stimulates the transcription of Fos (through intermediate activation of a protein called Elk). In a second pathway, PLC binds directly to activated LAT and is then phosphorylated by Zap-70. Activated PLC leads to the cleavage of PIP2 to IP3 and DAG. Although DAG activates protein kinase C (PKC), it is IP3 that causes a release of calcium into the cytosol. 15. Damage to neurons in patients with multiple sclerosis (MS) may be caused by autoreactive T cells that recognize peptides derived from myelin proteins presented by self MHC molecules. These autoreactive T cells secrete interferon (IFN)- and promote inflammation, which damages the myelin sheath surrounding neurons. The exact immunodominant epitopes recognized by autoreactive T cells in MS patents have been identified. One potential method of therapy for patients with MS is to administer therapeutic peptides that differ from the immunodominant epitopes by one or two amino acids. Which one of the following statements best describes the basis for this therapeutic approach? A. The therapeutic peptides, called “altered peptide ligands,” could inactivate T cells specific for myelin proteins, or drive them to differentiate into T cells that do not produce IFN- B. The therapeutic peptides, called “altered peptide ligands,” could interfere with processing of the natural myelin proteins by the patient’s antigen-presenting cells. C. The therapeutic peptides could bind to the TCRs of myelin-specific T cells but not to the self MHC molecules, thereby blocking T cell activation. D. The therapeutic peptides could down-regulate MHC expression.
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