Chapter 67: Review of the Immune System

7. A nurse is teaching a group of nursing students about immunoglobulins. Which statement by a student indicates a need for further teaching? a. "IgD provides a first line of defense against microbes entering the body through the lungs." b. "IgE plays a role in hypersensitivity reactions and responses to parasites." c. "IgG and IgM participate in the complement response to promote target cell lysis." d. "Neonatal immunity is the result of IgG crossing the placenta."

ANS: A IgD serves as a receptor for antigen recognition on B cells, which is the only place it is found. IgE is involved in hypersensitivity responses and responses to parasites. IgG and IgM are involved in complement responses. IgG crosses the placenta and confers passive immunity on the fetus.

1. Which immune responses can result in harm to the body? (Select all that apply.) a. Activation of the complement system b. Autoimmune response c. IgE binding to mast cells and basophils d. Opsonization e. Recognition of MHC molecules as nonself

ANS: B, C, E The autoimmune response causes the immune system to attack the body's own cells. The hypersensitivity response, mediated by IgE, causes the release of harmful chemical mediators. Recognition of MHC molecules as nonself in a transplanted organ can cause organ rejection. Activation of the complement system causes a cascade of reactions that assist in the immune response. Opsonization is a process that assists with phagocytosis.

4. Which statement is true about helper T cells? a. They are useful but are not essential to immune responses. b. They do not play a role in antibody production. c. They have highly specific receptors to antigens on their surface. d. They prevent CD4 molecules from attaching to antigens.

ANS: C Helper T cells have highly specific cell surface receptors that recognize individual antigens. Helper T cells play an essential role in several functions of the immune response. They have an essential role in the production of antibodies by B cells. They carry CD4 molecules on their surface and are also referred to as CD4 cells.

8. A patient who breast-feeds her infant asks the nurse about the immunity the infant receives from breast milk. What does the nurse tell the patient about immunity through breast-feeding? a. "The immunity protects the infant from hypersensitivity reactions." b. "The immunity provides phagocytes to help the infant fight infections." c. "The immunity results from the transfer of IgA through the breast milk." d. "The immunity protects the infant from respiratory and gastrointestinal (GI) microbes."

ANS: C IgA crosses breast milk and, in the GI tract, where it is not absorbed, provides passive immunity to microbes. Infants do not receive protection from hypersensitivity reactions through breast milk. Phagocytes are not transmitted through breast milk. Infants are not protected from respiratory microbes via breast milk.

9. A nurse is discussing the role of antibodies in the complement system with a group of nursing students. Which statement by a student is correct? a. "Antibodies activate the complement cascade by turning on the alternative pathway." b. "Antibodies that are free in solution can activate the complement system." c. "Antibodies flag target cells to be lysed by membrane attack complexes." d. "Antibody receptors are nonspecific to antigenic determinants."

ANS: C Lysis of target cells that have been tagged with antibodies is the most dramatic effect of the complement system. Antibodies activate the complement cascade by turning on the classical pathway. C1 cannot bind with free antibodies. Antibody receptors are specific to antigen determinants.

6. A nurse is teaching a group of nursing students about antibodies. The nurse correctly explains that which type of response is triggered when antigens bind to antibodies on mast cells or basophils? a. Acquired immune response b. Autoimmune response c. Hypersensitivity reaction d. Transplant rejection

ANS: C When antigens bind to antibodies on mast cells and basophils, chemical mediators of hypersensitivity reactions are released. Although hypersensitivity is an acquired response, mast cells and basophils do not play a role in other acquired responses. An autoimmune response occurs when the immune system fails to discriminate between self and nonself. Transplant rejection occurs when the MHC molecules of the donor are different from those of the patient.

1. A nurse is reviewing the immune system with a group of nursing students. One student asks about the difference between cell-mediated immunity and humoral immunity. What should the nurse reply? a. "Humoral immunity does not involve helper T cells in the immune response." b. "Humoral immunity does not have a role in hypersensitivity reactions." c. "Humoral immunity requires cytolytic T cells that attack antigens directly." d. "Humoral immunity uses cells produced by B lymphocytes in the immune response."

ANS: D Humoral immunity refers to immunity mediated by antibodies, which are produced by B lymphocytes. Helper T cells have an essential role in antibody production by B cells. The antibody immunoglobulin E plays a role in hypersensitivity reactions. Cytolytic T cells do not produce antibodies; they are key players in cellular immunity.

5. A nurse is caring for a patient who has undergone organ transplantation. Because the sequence of amino acids in the major histocompatibility complex (MHC) molecules of the donor is different from that of the patient, the nurse will expect to administer which class of drugs? a. Antibiotics b. Antihistamines c. Immune globulins d. Immunosuppressants

ANS: D The MHC molecules from one individual are recognized as foreign by the immune system of another individual; therefore, when an attempt is made to transplant organs between individuals who are not identical twins, immune rejection of the transplant is likely. Immunosuppressants are given to counter this response. Antibiotics are used to destroy bacteria. Antihistamines block hypersensitivity reactions. Immune globulins are given to confer passive immunity when specific acquired immunity has not yet developed a response.

3. A nurse is caring for a patient infected with the human immunodeficiency virus (HIV). Which finding would most concern the nurse? a. High level of macrophages b. Low neutrophil count c. Low red blood cell (RBC) count d. Very low helper T lymphocyte count

ANS: D The nurse understands that this patient may be vulnerable to opportunistic infections, especially if there were an indication of the HIV conversion to acquired immunodeficiency syndrome (AIDS). A very low helper T lymphocyte count would most concern the nurse, because the helper T cells are essential to the immune system, and people with AIDS have a low or deficient count. A high level of macrophages could indicate an inflammatory response. A low RBC count may indicate anemia. A low neutrophil count can be caused by multiple conditions, but a high count most likely indicates an infection.

10. A patient has a Type IV hypersensitivity (delayed-type hypersensitivity) response to an infection. The nurse understands that which two types of cells are necessary for this response? a. Antigen-presenting cells and mast cells b. Cytolytic T lymphocytes and target cells c. Immunoglobulin cells and dendritic cells d. Infected macrophages and CD4 helper T cells

ANS: D The object of Type IV hypersensitivity (delayed-type hypersensitivity) is to rid the body of bacteria that replicate within macrophages. The macrophage activates the CD4 cell, which in turn activates the macrophage. The other cells listed are not a part of this response.

2. A nurse is teaching a nursing student about a specific acquired immunity system. Which statement by the student indicates a need for further teaching? a. "Cell-mediated immunity and humoral immunity are both types of specific acquired immune responses." b. "Each exposure to an antigen causes a faster, more intense response." c. "Immune responses occur only after exposure to a foreign substance." d. "The skin is a factor in specific acquired immunity."

ANS: D The skin is a physical barrier that confers natural immunity. It is not a factor in specific acquired immunity. Cell-mediated and humoral immunity are both types of specific acquired immunity. In specific acquired immunity, each exposure to an antigen evokes a more intense response more quickly. Specific acquired immunity occurs only after initial exposure to an antigen.