Ch 8 Adaptive Immunity

21. Which statement is believed to be true concerning Th2 cells? a. Th2 cells are induced by antigens derived from allergens. b. They are induced by antigens derived from cancer cells. c. Th2 cells produce IL-2, TNF-ß, and IFN-γ. d. They assist in the development of cell-mediated immunity.

ANS: A Antigens derived from multicellular parasites and allergens are hypothesized to be involved in the production of more Th2 cells. Th1 cells are induced by antigens derived from cancer cells. Th2 cells produce IL-4, IL-5, IL-6, and IL-13.

15. The generation of clonal diversity occurs primarily during which phase of life? a. Fetal b. Neonatal c. Infancy d. Puberty

ANS: A Generation of clonal diversity primarily occurs in the fetus and probably continues to a low degree throughout most of adult life

13. An individual is more susceptible to infections of mucous membranes when he or she has a seriously low level of which immunoglobulin antibody? a. IgG b. IgM c. IgA d. IgE

ANS: C The IgA molecules found in bodily secretions are dimers anchored together through a J-chain and secretory piece. This secretory piece is attached to the IgA antibodies inside the mucosal epithelial cells and may function to protect these immunoglobulin antibodies against degradation by enzymes also found in the secretions, thus decreasing the risk of infections in the mucous membrane. The other options do not accurately identify the immunoglobulin antibody involved in mucous membrane infections.

Which are molecular classes of immunoglobulins? (Select all that apply.) a. IgC b. IgD c. IgE d. IgM e. IgN

B,C,D The five classes of immunoglobulin are IgG, IgA, IgM, IgD, and IgE.

11. Which immunoglobulin is present in blood, saliva, breast milk, and respiratory secretions? a. IgA b. IgE c. IgG d. IgM

ANS: A IgA can be divided into two subclasses, IgA1 and IgA2. IgA1 molecules are predominantly found in the blood, whereas IgA2 is the predominant class of antibody found in normal body secretions.

31. A student asks the healthcare professional how the aging process of the T-cell activity affects older adults. What response by the professional is best? a. Poor heat regulation abilities b. Increased risk for bone fractures c. Tendency to develop various infections d. Likelihood of experiencing benign skin lesions

ANS: C T-cell activity is deficient in older adults, and a shift in the balance of T-cell subsets is observed. These changes may result in increased susceptibility to infection. The other issues are not related to T-cell activity.

26. Which T cell controls or limits the immune response to protect the host's own tissues against an autoimmune response? a. Cytotoxic T cells b. Th1 cells c. Th2 cells d. Regulatory T (Treg) cells

ANS: D The regulatory T (Treg) cell's role is to control or limit the immune response to protect the host's own tissues against autoimmune reactions. Cytotoxic T cells attack and kill cellular targets directly. Th2 cells provide help for developing B cells and produce IL-4, IL-5, IL-6, and IL-13. Th1 cells are induced by antigens derived from cancer cells.

It is true that immunoglobulin E (IgE) is a. designed to protect the host from large viruses. b. the primary cause of common allergies. c. the only inflammatory cell that can damage a virus. d. normally found at high concentrations in the circulation.

B IgE, a mediator of common allergic responses, is an antibody that is designed to protect the host from parasites and is the only inflammatory cell that can damage a parasite. IgE is normally found in low concentrations in the circulation.

Which antigen is too small to initiate an immune response? a. Carrier b. Allergen c. Hapten d. Self-antigen

C A hapten is a molecule that is foreign but too small to induce an immune response alone. However, when it binds to a larger carrier molecule, it is able to induce an immune response. An allergen is an antigen that can induce an allergic response. A self-antigen is not foreign but has the three other criteria to be an immunogen.

A substance that is recognized as foreign or nonself is a. immunoglobulins. b. lymphocytes. c. antibodies. d. antigens.

D Antigens are recognized as foreign and initiate the immune response. Immunoglobulins and antibodies are part of the adaptive immune response; they attack the antigen. Lymphocytes are a type of blood cell that is part of the adaptive response.

Which term describes the type of immunity that occurs when preformed antibodies are transferred from a donor to a recipient? a. Passive b. Active c. Memory d. Cellular

A The two types of adaptive immunity are active and passive. Passive immunity occurs when preformed antibodies are transferred from a donor to a recipient. An example of passive immunity is the passage of maternal antibodies across the placenta to the fetus. Active immunity is produced by an individual after either a natural exposure or an immunization. Memory cells are formed through cellular and humoral immunity; they remember the antigen.

Which criteria influence the degree of immunogenicity? (Select all that apply.) a. Foreignness to the host b. Appropriate size c. Appropriate quantity d Chemical simplicity e. Chemical complexity

A, B, C, E The four criteria that influence the degree of immunogenicity are foreignness to the host, appropriate size, appropriate quantity, and chemical complexity.

24. The healthcare professional working with older adults teaches general infection-prevention measures as a priority for this age group due to which change in lymphocyte function? a. Increased production of antibodies against self-antigens b. Decreased number of circulating T cells c. Decreased production of autoantibodies d. Increased production of helper T cells

ANS: A B-cell function is altered with age as shown by decreases in specific antibody production in response to antigenic challenge, with concomitant increases in circulating immune complexes and in circulating autoantibodies (antibodies against self-antigens). Aging does not play a role in either decreasing T cells circulation or increasing helper T cells production.

9. The functions of the major histocompatibility complex (MHC) and CD1 molecules are alike because both do what? a. Are antigen-presenting molecules b. Bind antigens to antibodies c. Secrete interleukins during the immune process d. Are capable of activating cytotoxic T lymphocytes

ANS: A MHC and CD1 molecules are both antigen presenting molecules (APCs). Antigen binding fragments bind antigens to antibodies. Interleukins have many sources, but they are not secreted by MHCs and CD1 molecules. Activating cytotoxic T lymphocytes requires the presence of antigen presentation and effector Th cells.

30. Which cell has a role in developing cell-mediated immunity? a. Th1 b. CD4 c. CD8 d. Th2

ANS: A Only Th1 cells help develop cellular immunity.

5. What type of immunity is produced when an immunoglobulin crosses the placenta? a. Passive-acquired immunity b. Active-acquired immunity c. Passive-innate immunity d. Active-innate immunity

ANS: A Passive-acquired immunity (passive immunity) does not involve the host's immune response at all. Rather, passive immunity occurs when preformed antibodies or T lymphocytes are transferred from a donor to the recipient. This transfer can occur naturally, as in the passage of maternal antibodies across the placenta to the fetus, or artificially, as in a clinic using immunotherapy for a specific disease. The remaining options do not produce immunity via immunoglobulin transfer across the placenta.

3. What is the term for the process during which lymphoid stem cells migrate and change into either immunocompetent T cells or immunocompetent B cells? a. Clonal diversity b. Clonal differentiation c. Clonal selection d. Clonal competence

ANS: A The process is called the generation of clonal diversity and occurs in specialized (primary) lymphoid organs—the thymus gland for T cells and the bone marrow for B cells. Clonal differentiation, selection, and competence do not describe this process.

32. Which statement is true regarding maternal antibodies provided to the neonate? a. The antibodies enter into the fetal circulation by means of active transport. b. The antibodies are transferred to the fetus via the lymphatic system. c. The antibodies are directly related to the mother's nutritional intake. d. The antibodies reach protective levels after approximately 6 months of age.

ANS: A To protect the child against infectious agents both in utero and during the first few postnatal months, a system of active transport facilitates the passage of maternal antibodies into the fetal circulation. The antibodies are transmitted via the placenta and are related to the mother's immune system. The infant's own IgG-related antibodies reach protective levels by 6 months of age. The antibodies are not transferred via the lymphatic system, are not directly related to maternal nutrition, or reach protective levels after 6 months of age.

28. Which statement is true concerning IgM? a. IgM is the first antibody produced during the initial response to an antigen. b. IgM mediates many common allergic responses. c. IgM is the most abundant class of immunoglobulins. d. IgM is capable of crossing the human placenta.

ANS: A Typically, IgM is produced first (primary immune response), followed by IgG against the same antigen. IgE mediates allergic responses and is active in the defense against parasitic infections. IgG is the most abundant immunoglobulin class and can cross the human placenta to enter into fetal circulation.

CD4 is a characteristic surface marker and a result of which of these? (Select all that apply.) a. Activity in the primary lymphoid organs b. Process of cellular differentiation c. Alterations to T cells d. Changes to B cells e. Clonal selection

ANS: A, B, C, D Differentiation of B cells and T cells in the primary lymphoid organs results in the expression of several characteristic surface markers, such as CD4 on helper T cells, CD8 on cytotoxic T cells, and CD21 and CD40 on B cells. Clonal selection is the process during which antigens select those lymphocytes with complementary T-cell receptors (TCRs) or BCRs.

What are the necessary components of an adaptive immune response? (Select all that apply.) a. Antigen b. Gamma IgG c. Lymphocyte surface receptors d. Crystalline fragment e. Antibody

ANS: A, C, E Antigens are the molecules that can react with components of the adaptive immune system, including antibodies and lymphocyte surface receptors. Gamma IgG and crystalline fragment are not necessary components of an adaptive immune response.

4. Which type of immunity is produced by an individual after either natural exposure to the antigen or after immunization against the antigen? a. Passive-acquired immunity b. Active-acquired immunity c. Passive-innate immunity d. Active-innate immunity

ANS: B An individual produces active-acquired immunity (active immunity) after natural exposure to an antigen or after immunization, whereas passive-acquired immunity (passive immunity) does not involve the host's immune response at all. The innate immune system, also known as nonspecific immune system and the first line of defense, is composed of the cells and mechanisms that defend the host from infection by other organisms in a nonspecific manner, which means that the cells of the innate system recognize and respond to pathogens in a generic way.

20. Which statement is believed to be true concerning Th1 cells? a. Th1 cells are induced by antigens derived from allergens. b. They are induced by antigens derived from cancer cells. c. Th1 cells produce IL-4, IL-5, IL-6, and IL-13. d. They assist in the development of humoral immunity.

ANS: B Antigens derived from viral or bacterial pathogens and those derived from cancer cells are hypothesized to induce a greater number of Th1 cells relative to Th2 cells. The other statements are not true regarding Th1 cells.

27. Evaluation of umbilical cord blood can confirm that which immunoglobulin level is near adult levels? a. IgA b. IgG c. IgM d. IgE

ANS: B At birth, the total IgG level in the umbilical cord is the only immunoglobulin that is near adult levels. This is due to a system of active transport that facilitates the passage of maternal antibodies into the fetal circulation. The other antibodies are not present at this level in the newborn.

7. Which characteristic is the most important determinant of immunogenicity when considering the antigen? a. Size b. Foreignness c. Complexity d. Quantity

ANS: B Foremost among the criteria for immunogenicity is the antigen's foreignness. A self-antigen that fulfills all of these criteria except foreignness does not normally elicit an immune response. Thus most individuals are tolerant of their own antigens. The immune system has an exquisite ability to distinguish self (self-antigens) from nonself (foreign antigens). Size, complexity, and quantity are considered when determining immunogenicity but not to the extent that foreignness is.

18. Which cytokine is needed for the maturation of a functional helper T cell? a. IL-1 b. IL-2 c. IL-4 d. IL-12

ANS: B Of the options provided, IL-2 production is critical for the Th cell to mature efficiently into a functional helper cell.

Which is an example of an endogenous antigen? a. Yeast b. Cancer cells c. Bacteria d. Fungus

ANS: B Of the options provided, endogenous antigens include only those uniquely produced by cancerous cells.

25. How do antibodies protect the host from bacterial toxins? a. Lysing the cell membrane of the toxins b. Binding to the toxins to neutralize their biologic effects c. Inhibiting the synthesis of DNA proteins needed for growth d. Interfering with the DNA enzyme needed for replication

ANS: B To cause disease, most toxins must bind to surface molecules on the individual's cells. Protective antibodies can bind to the toxins, prevent their interaction with cells, and neutralize their biologic effects. Antibodies do not lyse the toxin cell membrane, inhibit the synthesis of DNA, or interfere with DNA replication.

12. Which antibody initially indicates a typical primary immune response? a. IgG b. IgM c. IgA d. IgE

ANS: B Typically, IgM is produced first (primary immune response), followed by IgG against the same antigen. IgA and IgE are not involved in the typical primary immune response.

1. Which primary characteristic is unique for the immune response? a. The immune response is similar each time it is activated. b. The immune response is specific to the antigen that initiates it. c. The response to a specific pathogen is short term. d. The response is innate, rather than acquired.

ANS: B Unlike inflammation, which is nonspecifically activated by cellular damage and pathogenic microorganisms, the immune response is primarily designed to afford long-term specific protection (i.e., immunity) against particular invading microorganisms; that is, it has a memory function. The inflammatory response is similar each time it is activate. Passive immunity is short term or temporary. The inflammatory process is innate.

23. Vaccinations are able to provide protection against certain microorganisms because of what? a. Strong response from IgM b. Level of protection provided by IgG c. Memory cells for IgE d. Rapid response from IgA

ANS: B Vaccinations provide protection by a secondary response when the individual is exposed to the microorganism to which he or she was vaccinated. At that time, IgG production is considerably increased, making it the predominant antibody class of the secondary response. IgM is more active against the primary exposure. IgE is usually seen in allergies. IgA is the predominant secretory antibody and prevents the attachment and invasion of pathogens through mucosal membranes.

36. Which statements are true concerning the humoral immune response? (Select all that apply.) a. The humoral immune response is divided into major and minor phases. b. The response has IgG and IgM produced during each of its phrases. c. It has a greater presence of IgG than IgM in one of its phases. d. The humoral immune response is produced in reaction to the presence of an antigen. e. Phases differ in their response time as a result of the effect of memory cells.

ANS: B, C, D, E The humoral immune response is divided into two phases, primary and secondary. These phases differ in the relative amounts of IgG produced—the secondary response having a significantly higher proportion of IgG relative to IgM. The two phases also differ in the speed with which each occurs after the antigen challenge—the secondary phases is significantly more rapid than the primary phase because of the presence of memory cells in the secondary phase.

10. Where are antibodies produced? a. Helper T lymphocytes b. Thymus gland c. Plasma cells d. Bone marrow

ANS: C An antibody or immunoglobulin is a serum glycoprotein produced only by plasma cells in response to a challenge by an immunogen. Antibodies are not produced by the thymus gland, bone marrow, or by helper T lymphocytes.

2. In which structure does B lymphocytes mature and undergo changes that commit them to becoming B cells? a. Thymus gland b. Regional lymph nodes c. Bone marrow d. Spleen

ANS: C B lymphocytes mature and become B cells in specialized (primary) lymphoid organs—the thymus gland for T cells and the bone marrow for B cells. Neither regional lymph nodes nor the spleen are involved in changing B lymphocytes into B cells.

29. Which cell has the ability to recognize antigens presented by the MHC class I molecules? a. T cytotoxic b. CD 4 c. CD 8 d. T helper

ANS: C CD8 cells recognize antigens presented by the major histocompatibility complex (MHC) class I molecules and become mediators of cell-mediated immunity and directly kill other cells (T-cytotoxic cells). CD4 cells tend to recognize antigen presented by MHC class II molecules and develop into helpers in the later clonal selection process (T-helper cells).

19. Th2 cells produce IL-4 and suppress which cells? a. B lymphocytes b. Cytotoxic T lymphocytes c. Th1 cells d. Memory T lymphocytes

ANS: C Th2 cells produce IL-4, which suppresses only Th1 and Th17 cells through their IL-4 receptors.

6. The portion of the antigen that is configured for recognition and binding is referred to as what type of determinant? a. Immunotope b. Paratope c. Epitope d. Antigenitope

ANS: C The precise portion of the antigen that is configured for recognition and binding is called its antigenic determinant or epitope. The other terms are not discussed in the text.

16. A student is confused about the process of the generation of clonal diversity. What description by the professor is best? a. It involves antigens that select those lymphocytes with compatible receptors. b. It allows the differentiation of cells into antibody-secreting plasma cells or mature Peyer patches. c. It takes place in the primary (central) lymphoid organs. d. It causes antigens to expand and diversify their populations.

ANS: C This process occurs in central lymphoid organs—the thymus gland for T cells and bone marrow for B cells. It does not involve antigens selecting lymphocytes or expanding and diversifying. It does allow the differentiation of lymphoid stem cells into B and T lymphocytes. Payer patches are lymphoid organs found in the intestines.

35. Which is an example of a bacterial toxin that has been inactivated but still retains its immunogenicity to protect the person? (Select all that apply.) a. Poliomyelitis b. Measles c. Tetanus d. Gonorrhea e. Diphtheria

ANS: C,E The symptoms of tetanus or diphtheria are mediated by specific toxins. To prevent harming the recipient of the immunization, bacterial toxins are chemically inactivated so that they have lost most of their harmful properties but still retain their immunogenicity. These agents are referred to as toxoids. Poliomyelitis, measles, and gonorrhea are not examples.

22. When a person is exposed to most antigens, antibodies can be usually detected in their circulation within what timeframe? a. 12 hours b. 24 hours c. 3 days d. 6 days

ANS: D After approximately 5 to 7 days is an IgM antibody specific for that antigen detected in the circulation.

33. Antibodies that are associated with mucosal immune system, such as immunoglobulins, function to prevent which type of infections? a. Infections that attack the respiratory system b. Infections that tend to be chronic in nature c. Infections likely to be resistant to antibiotics d. Infections that focus on epithelial surfaces of the body

ANS: D Antibodies of the systemic immune system function throughout the body, whereas antibodies of the secretory (mucosal) immune system—primarily immunoglobulins of the IgA class—are associated with bodily secretions and function to prevent pathogenic infection on epithelial surfaces. The other options are not necessarily true when considering the immunoglobulins.

34. Cytokines are vital to a cell's ability to do which function? a. Excrete b. Reproduce c. Metabolize d. Communicate

ANS: D During their interactions, cells must communicate with each other through soluble cytokines. The other options are not so rigidly related to cytokines.

8. A student asks why some vaccinations are given orally and some are given by injection. What response by the professor is best? a. Different routes allow the speed of onset of the antigen to be varied, with the intravenous route being the fastest. b. Some individuals appear to be unable to respond to an antigen by a specific route, thus requiring the availability of different routes for the same antigen. c. Antigen-presenting cells are highly specialized and thus require stimulation by different routes. d. Each route stimulates a different lymphocyte-containing tissue, resulting in different types of cellular and humoral immunity.

ANS: D Each route preferentially stimulates a different set of lymphocyte-containing (lymphoid) tissues and therefore results in the induction of different types of cell-mediated or humoral immune responses. The speed of onset of the antigen, individual differences in response, and the requirement for different routes to stimulate different antigen-presenting cells are not accurate descriptions of why different routes of immunization are used.

14. How does the B-cell receptor (BCR) complex function? a. Communicating information about the antigen to the helper T cell b. Secreting chemical signals to communicate between cells c. Releasing histamine and other vasoactive substances d. Communicating information about the antigen to the cell nucleus

ANS: D The role of the BCR is to recognize the antigen; however, unlike circulating antibodies, the receptor must communicate that information to the cell's nucleus. The BCR does not communicate information about the antigen to the helper T cell or secrete chemical signals to communicate between cells. The release of histamine and other vasoactive substances is part of inflammation, not adaptive immunity.

What is the precise portion of the antigen that is configured for recognition and binding of an antibody? a. Paratope b. Epitope c. Self-antigen d. Immunogen

B The antigenic determinant or epitope is the precise portion of the antigen that is configured for recognition and binding of an antibody. A paratope is the matching portion on the antibody or lymphocyte receptor. A self-antigen is one that is not foreign to the host. An immunogen is an antigen that induces an immune response.

Which statement best describes the cells and their functions in the humoral arm of the immune system? a. Cells undergo differentiation and develop into subpopulations. b. Cells attack cancerous cells. c. Antibodies are primarily responsible for protection. d. Cells in the humoral arm are also called cellular immunity.

C Antibodies are primarily responsible for protection against viruses and bacteria and are part of the humoral arm of the immune system. The antibody can directly invade a microorganism or activate the immune response. T cells undergo differentiation, attack cancerous cells, and are part of cellular immunity.

Which statement is true regarding aging and the immune system function? a. Older adults have decreased circulating antibodies. b. T-cell function is increased. c. Antibody production to specific antigens is inferior. d. Response to infection is rapid.

C T-cell function is decreased, and immune responses are delayed. B-cell production is inferior; however, the cells have increased circulating antibody levels.

Which statement is true regarding immunoglobulin A (IgA) antibodies? a. IgA-2 is predominantly found in blood. b. IgA-1 is predominantly found in the body's secretions. c. The J chain anchors together the IgA molecules. d. IgA is the most predominant immunoglobulin.

C The J chain anchors together the IgA molecules to form dimers and helps them resist degradation from enzymes. IgA-1 is found in the blood, and IgA-2 is found in the secretions of the body. IgG, not IgA, is the most predominant immunoglobulin.

Which statement is true regarding the immune response in humans? a. Before birth, lymphocytes are not produced. b. B lymphocytes come from the thymus. c. The thymus releases mature lymphocytes. d. Generation of clonal diversity occurs in primary lymphoid organs.

D Generation of clonal diversity occurs in the primary lymphoid organs, which includes the thymus (T lymphocytes) and bone marrow (B lymphocytes). In the fetus, lymphocytes undergo extensive differentiation and proliferation that recognize almost any foreign antigen predominate. The thymus releases immature T cells that have the ability to recognize foreign antigens.