Chap 11 Innate and Adaptive Immunity
A mother brings her 5-month-old infant to the pediatrician for recurrent colds. The mother has never breast-fed and the infant is fed iron-fortified formula. The mother asks, "My baby has been perfectly healthy up until last month—now it seems like she has been sick constantly. Why?" How should the physician respond?
"An infant gets immunity from the mother at birth and from breast milk; this provides protection from infection but wears off in approximately 3 to 6 months. An infant still needs time for his own immune system to mature." Explanation: The infant's immune system is not yet mature. Passive immunity is immunity transferred from mother to fetus before birth. After birth, the neonate receives IgG antibodies from the mother in breast milk or colostrum. Therefore, infants are provided with some degree of protection from infection for approximately 3 to 6 months, giving their own immune systems time to mature.
A client with infectious mononucleosis asks the nurse why the lymph nodes are enlarged. Which statement is the nurse's appropriate response?
"Your lymph nodes trap and destroy viruses." Explanation: The lymph nodes remove foreign material from the lymph system before the fluid can enter the bloodstream. Mononucleosis is an infection caused by the Epstein-Barr virus. The lymph nodes trap the virus where the lymphocytes and macrophages can destroy it. Enlargement may occur with increased production of lymphocytes, backup of lymph fluid, or malignancy.
Which client is at the greatest risk for developing an intracellular pathogen infection?
A client with AIDS who has a decreased CD4+ TH1 count Explanation: Thus, the CD4+ TH1 cell controls and coordinates host defenses against certain intracellular pathogens, a function that helps to explain why a decreased CD4+ TH1 count in persons with acquired immunodeficiency syndrome (AIDS) places them at high risk for intracellular pathogen infections. If the teenager has a healthy immune system, high school should not place him or her at high risk for infection. A WBC of 8000 is normal. Radioactive iodine attacks the thyroid gland and does not usually interfere with immunity.
A client is brought to the physician's office with a raised, red macular rash on the trunk and arms accompanied by a fever. A diagnosis of measles is made. Which type of immunity does this disease process provide?
Active natural immunity Explanation: Active immunity is acquired when the host mounts an immune response to an antigen either through the process of vaccination (artificial means) or from environmental exposure (natural means). It is called active immunity because it requires the host's own immune system to develop an immunologic response
A client is brought to the physician's office with a raised, red macular rash on the trunk and arms accompanied by a fever. A diagnosis of measles is made. Which type of immunity does this disease process provide?
Active natural immunity Explanation: Active immunity is acquired when the host mounts an immune response to an antigen either through the process of vaccination (artificial means) or from environmental exposure (natural means). It is called active immunity because it requires the host's own immune system to develop an immunologic response.
The cells that mediate humoral immunity do so because they are capable of producing:
Antibodies Explanation: B lymphocytes (B cells) are the only cells capable of producing antibodies; therefore, they are the cells that mediate humoral immunity. B lymphocytes (B cells) differentiate into plasma cells that produce the needed immunoglobulins (antibodies) for responding to that particular antigen. Stem cells are undifferentiated cells. T helper cells differentiate into cytotoxic and other T-cell forms.
Substances foreign to the host that can stimulate an immune response are known as:
Antigens Explanation: Antigens are foreign substances that stimulate an immune response. Antibodies are innate and will adapt to the antigen. MHC proteins aid in the identification process of host cells. Cytokines are signaling molecules of the immune system.
An infectious disease nurse is researching T-cells to determine which cells control replication of intracellular bacteria. Which cells should the nurse begin investigating?
CD8 cells Explanation: All viruses and some bacteria multiply in the cytoplasm of infected cells. Once inside cells, these pathogens replicate and are not accessible to antibodies. They can be eliminated only by the destruction or modification of the infected cells. The elimination of infected cells without the destruction of healthy tissue requires the cytotoxic mechanisms of CD8 T cells. Therefore, the CD8 cytotoxic T cells are especially important in controlling replicating viruses and intracellular bacteria.
Which findings are considered part of normal aging? Select all that apply.
Decrease in CD4+ count Decreased IL-2 level Explanation: There is a decrease in the size of the thymus gland, which is thought to affect T-cell function. A suggested biologic clock in T cells that determines the number of times it divides may regulate cell number with age. Some researchers have reported a decrease in the absolute number of lymphocytes, and others have found little, if any, change. The most common finding is a slight decrease in the proportion of T cells to other lymphocytes and a decrease in CD4+ and CD8+ T cells. Evidence indicates that aged T cells have a decreased rate of synthesis of the cytokines that drive the proliferation of lymphocytes and a diminished expression of the receptors that interact with those cytokines. For example, it has been shown that IL-2, IL-4, and IL-12 levels decrease with aging. Although B-cell function is compromised with age, the range of antigens that can be recognized is not diminished.
A clinical research study is evaluating cells that bridge both the innate and adaptive immune systems. A nurse has identified the dendritic cells (DCs) as a key component. Which statement validates this finding?
Dendritic cells (DCs) directly sense pathogens, capture foreign agents, and transport them to secondary lymphoid tissues. Once activated, they undergo a maturation process and function as antigen-presenting cells (APCs) capable of initiating adaptive immunity. Explanation: Dendritic cells (DCs) are specialized, bone marrow-derived leukocytes found in lymphoid tissue and are the bridge between the innate and adaptive immune systems. They are present primarily in an immature form that is available to directly sense pathogens, capture foreign agents, and transport them to secondary lymphoid tissues. Once activated, DCs undergo a complex maturation process in order to function as key antigen-presenting cells (APCs) capable of initiating adaptive immunity. They are responsible for the processing and presentation of foreign antigens to the lymphocytes.
Select the statement that best describes the effectiveness of vaccination in the older adult population.
Experimental evidence suggests that vaccination is less successful in inducing immunization in older persons than in younger adults. Explanation: Older adults tend to be more susceptible to infections, have more evidence of autoimmune and immune complex disorders than younger persons, and have a higher incidence of cancer. Experimental evidence suggests that vaccination is less successful in inducing immunization in older persons than in younger adults. However, the effect of altered immune function on the health of older adults is clouded by the fact that age-related changes or disease may affect the immune response.
A lactation nurse visits a new mother after delivery of her first child and encourages the mother to breast-feed her infant, even for a short time. Which statement made by the nurse correctly explains the importance of breast-feeding?
For several months, colostrum will provide the infant with passive immunity to diseases to which the mother has immunity. Explanation: After birth, the neonate receives IgG antibodies from the mother in breast milk or colostrum. Therefore, infants are provided with some degree of protection from infection for approximately 3 to 6 months, giving their own immune systems time to mature. IgA is primarily a secretory Ig that is found in saliva, tears, colostrum (i.e., first milk of a nursing mother), and bronchial, gastrointestinal, prostatic, and vaginal secretions. Its primary function is in local immunity on mucosal surfaces. IgA prevents the attachment of viruses and bacteria to epithelial cells.
A client has recently received a pneumococcal vaccine and the client's B cells are consequently producing antibodies. Which cells may enhance this production of antibodies?
Helper T cells Explanation: In order for B lymphocytes to produce antibodies, they require the help of specific T lymphocytes, called helper T cells, which help B lymphocytes produce antibodies. Natural killer cells as well as regulatory and cytotoxic T cells do not perform this function.
A client has recently received a pneumococcal vaccine and the client's B cells are consequently producing antibodies. Which cells may enhance this production of antibodies?
Helper T cells Explanation: In order for B lymphocytes to produce antibodies, they require the help of specific T lymphocytes, called helper T cells, which help B lymphocytes produce antibodies. Natural killer cells as well as regulatory and cytotoxic T cells do not perform this function
A client receives an interleukin-2 (IL-2) infusion to treat cancer. Which response explains how this cytokine will affect the growth of cancer cells?
IL-2 stimulates growth of cytotoxic T lymphocytes. Explanation: Cytokines are small proteins used by the innate and adaptive immune systems to communicate with each other. IL-2 is a growth factor for activated T cells produced by macrophages. IL-2 activates cytotoxic T lymphocytes and natural killer cells. These cells destroy abnormal cells.
Which immunoglobulin is primarily found in secretions and has a primary function of providing local immunity on mucosal surfaces?
IgA Explanation: IgA is found in saliva and tears, and is a primary defense against infections in mucosal tissues. IgM is the first immunoglobulin to appear in response to antigen invasion. IgG is the most abundant immunoglobulin and can cross the placenta. IgD is an antigen receptor on B-cell membranes.
Which immunoglobulin is primarily found in secretions and has a primary function of providing local immunity on mucosal surfaces?
IgA Explanation: IgA is found in saliva and tears, and is a primary defense against infections in mucosal tissues. IgM is the first immunoglobulin to appear in response to antigen invasion. IgG is the most abundant immunoglobulin and can cross the placenta. IgD is an antigen receptor on B-cell membranes.
Which immunoglobulin (Ig) is released in response to allergy or parasitic infections?
IgE Explanation: IgE is secreted in response to inflammation and allergy and is released in the presence of parasitic infection. IgG is responsible for antiviral, antitoxin, and antibacterial responses. IgA is found in body secretions and helps with local immunity on mucosal surfaces. IgM is the first antibody developed by an infant. IgD helps B cells mature.
The nurse is aware that the only class of immunoglobulins to cross the placenta is:
IgG Explanation: IgG is the only class of immunoglobulins to cross the placenta. Levels of maternal IgG decrease significantly during the first 3 to 6 months of life, while infant synthesis of immunoglobulins increases.
Which immunoglobulin (Ig) is the most abundant of circulating antibodies?
IgG Explanation: IgG makes up about 75% of the immunoglobulins. IgA is about 15%, IgM 10%, and IgE 0.004% of the total.
A nurse is caring for a child diagnosed with DiGeorge syndrome with thymic hypoplasia. Which immune response would the nurse anticipate in this child?
Increased risk of infection Explanation: The thymus is essential to the development of the immune system because it is responsible for the production of mature, immunocompetent T lymphocytes. Mature, immunocompetent T-helper and T-cytotoxic cells leave the thymus in 2 to 3 days and enter the peripheral lymphoid tissues through the bloodstream. Without a thymus, infections would occur frequently. These T cells recognize foreign antigens and build an immune response. Therefore, with thymic hypoplasia, there is a risk for increased infection (not reduced infection or no change). Obviously, there is an antigen response.
Select the phases that make up the reaction of the complement system.
Initial activation, amplification of inflammation, membrane attack response Explanation: The reactions of the complement system can be divided into three phases: (1) initial activation, (2) amplification of inflammation, and (3) membrane attack response. The other options are not part of the system.
An obstetrics nurse is counseling an expectant mother. The mother is concerned about letting people hold her baby once the baby is born, fearing that the infant will get sick. What should the nurse explain to the mother?
Maternal immunoglobulins cross the placenta and protect the newborn early in life. Explanation: Passive immunity is immunity transferred from another source. An infant receives passive immunity naturally from the transfer of antibodies from its mother in utero and through breast milk. Maternal IgG crosses the placenta and protects the newborn during the first few months of life. Innate immunity are not effective yet, and protection is unrelated to the amount of lymphoid tissue.
A person has been exposed to a particular antigen and a now experiences a repeat exposure. What stimulates a quicker immune response?
Memory T cells Explanation: The memory T and B lymphocytes that are generated remain in the body for a longer time and can respond more rapidly during repeat exposures to an antigen related to their acquired memory.
While caring for a pediatric client admitted with a viral infection, the nurse knows that which type of cell will be the child's primary defense against the virus?
Natural killer (NK) cells Explanation: The third type of lymphocyte, the natural killer (NK) cell is part of the innate immune system and may be the first line of defense against viral infections. The NK cell also has the ability to recognize and kill tumor cells, abnormal body cells, and cells infected with intracellular pathogens, such as viruses and intracellular bacteria. Complement is activated in the inflammatory response. Leukotrienes and bradykinin are also a part of the inflammatory response.
A child has a congenital condition in which the thymus gland is absent. What should the nurse include in the education of care of this client to the parents?
Observe and report signs and symptoms of infection. Explanation: The thymus is essential to the development of the immune system because it is responsible for the production of mature, immunocompetent T lymphocytes.
The process by which microbes are coated to allow for more efficient recognition by phagocytes is known as:
Opsonization Explanation: Opsonization is the coating of particles with proteins, lectins, and complement to make them more attractive for phagocytes to recognize them as a foreign pathogen. Immunization is the process of acquiring the ability to respond to an antigen after its administration by vaccine. Immunity is protection from disease and, more specifically, infectious disease. Memory response occurs on second or subsequent exposures to the antigen.
A woman experiences a viral infection while pregnant. Which type of immunity does an infant have at birth against this infection?
Passive Explanation: Passive immunity is when the antibodies against an antigen are transferred directly to the host, such as when a fetus gains from the mother's immune system. Active immunity is acquired through exposure to antigens, and having the B and T lymphocytes develop a response. Tolerance is the ability of the immune system to react to foreign substances but not the body cells. Adaptive immunity is when the immune system responds to antigens and is moderated by B and T lymphocytes.
Activating lymphocytes depends on which actions of antigens by macrophages?
Processing and displaying Explanation: Macrophages engulf and process the antigen, then move it to the surface for display to a T lymphocyte. Macrophages do not completely destroy antigens; the T and B cells do the destruction after the processed antigen is presented. Memory cells remember the first encounter with a particular antigen and repeat the same response. Macrophages capture one antigen at a time, not in clusters or in groups.
The nurse is planning care for a client with a diagnosis of primary immunodeficiency. What is a priority intervention to incorporate into the plan?
Protecting the client from infection Explanation: The client with immunodeficiency has an absent or inadequate immune response. Cell-mediated, or cellular, immunity is mediated by the cytotoxic T lymphocytes (T cells) and functions in the elimination of intracellular pathogens. A lack of this response increases the client's risk of infection.
The results of recent research suggest that a key role in the origin of some diseases is played by inflammation. For which disease is it thought that inflammation has a role in its beginnings?
Rheumatoid arthritis Explanation: Among the functions of the innate immune system is induction of a complex cascade of events known as the inflammatory response. Recent evidence suggests that inflammation plays a key role in the pathogenesis of a number of disorders such as atherosclerosis and coronary artery disease, bronchial asthma, type 2 diabetes mellitus, rheumatoid arthritis, multiple sclerosis, and systemic lupus erythematosus. Osteoporosis is the abnormal loss of bone tissue and density. Osteogenesis imperfecta is a genetic disease causing multiple bone fractures in a newborn. Hydronephrosis is a condition of the kidney causing distention of the pelvis and calyces because of an obstruction in the ureter causing an inability of urine to pass.
Which physiologic characteristics correspond with innate immunity? Select all that apply.
Similar immune response for each exposure Immediate response to antigen invasion Explanation: Innate immunity is immediate, but it is limited to certain general classes of microbes instead of to specific organisms. The response to each infection is similar; some defenses are the epithelium of the skin and mucous membranes along with inflammation and fever. Cellular components of innate immunity include phagocytes, natural killer cells, and dendritic cells. Cytokines, complement proteins, acute-phase proteins, and soluble mediators are molecular components of the innate immunity.
The first physical line of defense in innate immunity is:
Skin and mucous membranes Explanation: The first physical line of defense are the skin and mucous membranes, which prevent pathogens from entering. Plasma proteins, neutrophils, and specialized lymphocytes are examples of cellular level protection.
A newborn has been lethargic, is not nursing well, and is basically looking ill. Following lab tests, it has been found that the newborn has IgM present in his blood. How should the nurse interpret this finding?
The presence of IgM suggests the infant has a current infection. Explanation: IgM is the first immunoglobulin to appear in response to antigen and is the first antibody type made by a newborn. This is diagnostically useful because the presence of IgM suggests a current infection in the infant by a specific pathogen. IgE is involved in inflammation, allergic responses, and combating parasitic infections. It binds to mast cells and basophils. The binding of antigen to mast cell- or basophil-bound IgE triggers these cells to release histamine and other mediators important in inflammation and allergies. IgA is found in saliva and tears, and is a primary defense against infections in mucosal tissues.
In an attempt to best explain the innate immune system to a class of first-year nursing students, the instructor should describe what characteristic?
The response of the innate immune system is rapid, usually within minutes to hours, and prevents the establishment of infection and deeper tissue penetration of microorganisms. Explanation: The innate immune system is the first line of defense. The adaptive immune system is composed of lymphocytes and their products. Antibodies comprise humoral immunity and T-cells provide cellular immunity.
A client seeks treatment in the clinic for exposure to poison ivy with a rash over the right arm and hand. The nurse is aware that what toxin is found in the oils on poison ivy that is responsible for eliciting an allergic reaction?
Urushiol Explanation: Urushiol is a toxin found in the oils on poison ivy that is responsible for initiating an allergic reaction.
The entrance of a microbe into an individual's vascular space has initiated opsonization. How will the health care provider explain this process that is critical in stopping the infiltration of the microbe through opsonization? Opsonization:
coats a microbe to activate phagocytosis recognition. Explanation: The coating of particles, such as microbes, is called opsonization, and the coating materials are called opsonins. The opsonin bound to the microbe then activates the phagocyte after attachment to a complementary receptor on the phagocyte. Opsonization does not involve stimulation by T cells, stimulation of the bone marrow, or the lysis of microbes by cytotoxic T cells.
While explaining immunity to a client, the nurse responds, "The body's internal organs are protected from pathogens because:
our mucosal tissue contains all the necessary cell components to fight a pathogen with an immune response." Explanation: Secondary lymphoid tissues contain all the necessary cell components (i.e., T cells, B cells, macrophages, and dendritic cells) for an immune response. Because of the continuous stimulation of the lymphocytes in these tissues by microorganisms constantly entering the body, large numbers of plasma cells are evident. Immunity at the mucosal layers helps to exclude many pathogens and thus protects the vulnerable internal organs. Although cells of both the innate and adaptive immune systems communicate critical information by cell-to-cell contact, many interactions and effector responses depend on the secretion of short-acting soluble molecules called cytokines. The actions of cytokines are often pleiotropic and redundant. Pleiotropism refers to the ability of a cytokine to act on different cell types.
