Chapter 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 nurse is teaching a new mother diagnosed with HIV about the transfer of the infection to her newborn. The mother begins to cry and states, "It's too late, the lab tests on my baby are already positive for HIV." How should the nurse respond?

"Just because the test is positive for HIV does not mean your baby is infected with the virus." Explanation: Because of maternal transfer of IgG antibodies to the fetus, an infant born to a mother infected with HIV has a positive HIV antibody test result, although the child may not be infected with the virus.

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.

Once T helper cells are activated, they secrete which substance that activates and influences nearly all of the other cells of the immune system?

Cytokines Explanation: Cytokines activate and regulate B cells, cytotoxic T cells, natural killer (NK) cells, macrophages, and other immune cells. The ability of the cells of both the innate and adaptive immune systems to communicate critical information with each other and initiate effector cell responses is dependent upon the secretion of short-acting, biologically active, soluble substances called cytokines. Complement is activated in the inflammatory response. Leukotrienes and bradykinin are also a part of the inflammatory response.

Which cells block the entry of microbes and destroy them by secreting antimicrobial enzymes, proteins, and peptides within the mucous membrane linings of the gastrointestinal, respiratory, and urogenital tract?

Epithelial Explanation: Epithelial cells line the body systems and are joined by tight junctions to protect from invasion. Lymphatic tissue underlies the epithelia as a secondary barrier. Immune cells are present everywhere but are not used to line tissues. Leukocytes are white blood cells.

The laboratory finds IgA in a sample of cord blood from a newborn infant. This finding is important because it signifies what?

Fetal reaction to exposure to an intrauterine infection Explanation: Cord blood does not normally contain IgM or IgA. If present, these antibodies are of fetal origin and represent exposure to intrauterine infection.

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 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.

Adaptive immune responses, also called acquired or specific immunity, are composed primarily of which type of cells?

Lymphocytes Explanation: The adaptive immune system consists of lymphocytes that comprise the humoral (B cell) and cell-mediated (T cell) immune responses. Granulocytes, toll-like receptors, and the epithelial layer of tissue are all important components of the innate (first line of defense) immune response.

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.

A blood smear is being examined and a stain has been added that will identify granulocytes. Which cell types will be visible with the stain? Select all that apply.

Neutrophil Eosinophil Basophil Explanation: The macrophage does not contain cytoplasmic granules, and neutrophils, eosinophils, and basophils do. The granules contain the mediators of the acute inflammatory response. Monocytes are not granulocytes.

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 responseoccurs on second or subsequent exposures to the antigen.

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.

A college student has received a tetanus booster shot. This immunization confers protection by way of what immune process?

Secondary humoral response Explanation: Booster immunizations make use of the memory, or secondary, response that is a component of humoral immunity. The secondary immune response occurs on subsequent exposure to the antigen. During the secondary response, the rise in antibody occurs sooner and reaches a higher level because of available memory cells. A primary response occurs on first exposure to an antigen. This immunization does not make use of the cell-mediated immune response of innate immunity.

A client is being evaluated for atopic dermatitis possibly caused by a latex-related allergic reaction. The nurse will review which lab results to determine if an allergy is present?

Serum IgE Explanation: IgE binds to mast cells and basophils and is involved in parasitic infections, as well as allergic and hypersensitivity reactions. Serum IgE causes the symptoms of allergic reactions and is elevated in type 1 hypersensitivity disorders.

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.

The nurse is explaining to a colleague the basis of a client's allergy to dust. What statement by the nurse most accurately describes antigens in this situation?

They are substances foreign to the host that can stimulate an immune response. Explanation: Antigens are any molecule that can stimulate an immune response. Antibodies are polypeptides. Cytokines communicate critical information. Interferons disrupt viral multiplication.

The most important function of the thymus is:

immune cell production and maturation. Explanation: The function of the thymus as a lymphoid organ is to generate mature immunocompetent T lymphocytes. The lymph nodes remove foreign material from lymph before it enters the bloodstream and serve as a center for proliferation and response of immune cells. The spleen filters antigens from the blood and responds to systemic infections.

A student asks, "What does cell-mediated immunity mean to the client?" The instructor responds, "This means:

the body is trying to defend itself against intracellular microbe invasion by engulfing and destroying the microbe." Explanation: Cell-mediated immunity, which defends against intracellular microbes such as viruses, is provided by cells called T lymphocytes. Some T lymphocytes activate phagocytes to destroy microbes that have been engulfed, whereas others kill any type of host cell that is harboring microbes.

Select the response that correctly identifies B lymphocytes.

They are the only cells 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 and differentiate into plasma cells, which produce antibody. The other options refer to T cells.

A nurse is planning to teach a parent group about the spread of infection, the importance of vaccines, and active immunity. Which statements should be included in the teaching plan? Select all that apply.

Active immunity can be acquired through the process of vaccination or from environmental exposure to an antigen. Active immunity allows the host's own immune system to develop an immunologic response. Active immunity is long-lasting and can improve on repeated exposures to an antigen. Explanation: Active immunity is acquired when the host mounts an immune response to an antigen either through the process of vaccination or from environmental exposure. It is called active immunity because it requires the host's own immune system to develop an immunologic response including the development of memory. Active immunity is usually long-lasting and with subsequent exposure the immune system rapidly becomes fully activated because of the presence of memory B and T lymphocytes and circulating antibodies. An acquired immune response can improve on repeated exposures to an injected antigen (booster vaccines) or a natural infection. Passive immunity is immunity transferred from another source. The most common form of passive immunity is that conferred from mother to fetus. Some protection against infectious disease can also be provided by the administration of Ig pooled from human or animal sources. Passive immunity produces only short-term protection that lasts weeks to months.

Passive immunity is immunity that is transferred from another source and lasts only weeks to months. What is an example of passive immunity?

An injection of γ-globulin (gamma-globulin) Explanation: Passive immunity also can be artificially provided by the transfer of antibodies produced by other people or animals. Some protection against infectious disease can be provided by the injection of hyperimmune serum, which contains high concentrations of antibodies for a specific disease, or immune serum or γ-globulin (gamma-globulin), which contains a pool of antibodies from many individuals providing protection against many infectious agents. Immunizations and allergy shots are examples of active immunity. Exposure to poison ivy can be the cause of a hypersensitivity reaction; it is not immunity.

Select the type of lymphocyte that matures in the bone marrow.

B lymphocytes Explanation: B lymphocytes mature in the bone marrow and are essential for humoral or antibody-mediated immunity. The T lymphocytes mature in the thymus. Macrophages are part of the monocytic phagocyte system, are in almost all tissues, and are the mature form of monocytes. Cytotoxic T cells are involved in cell-mediated immunity.

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 client's exposure to an antibiotic-resistant microorganism while in the hospital has initiated an immune response. Which process is responsible for the mediated and regulated actions that occur in this situation?

Cytokines released at cell-to-cell interfaces bind to specific receptors on the cells that they target Explanation: Most cytokines are released at cell-to-cell interfaces, where they bind to specific receptors on the membrane surface of their target cells and then activate intracellular processes. All cytokines are secreted in a brief, self-limited manner. They are not usually stored as preformed molecules. The short half-life of cytokines ensures that excessive immune responses and systemic activation do not occur. Cytokines are proteins, not cells, and are thus incapable of phagocytosis.

A nurse who works in a long-term care facility has observed the high incidence of infectious illnesses among the older adults who reside there. What is the best explanation for a diminished immune capacity in older adults?

Decreased numbers and responsiveness of T lymphocytes Explanation: Although this phenomenon is not well understood, increasing proportions of lymphocytes become unresponsive with age, and CD4+ T lymphocytes are the most severely affected. B lymphocytes recognize more antigens, not fewer, and expression of cytokines and their cellular receptors decreases.

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 client diagnosed with sepsis has a critically low neutrophil count. The nurse expects which drug or drug class to be used to stimulate white blood cell production?

Granulocyte CSF (G-CSF) such as filgrastim Explanation: Granulocyte CSF (G-CSF) promotes growth and maturation of neutrophils consumed in inflammatory reactions. In clinical practice, recombinant CSF is being used to increase the success rates of bone marrow transplantations and neutropenia. The availability of recombinant CSFs and cytokines offers the possibility of several clinical therapies where stimulation or inhibition of the immune response or cell production is desirable.

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.

The nurse is assisting a new mother with breastfeeding. What does the nurse understand is a primary secretory immunoglobulin (Ig) that is found in the colostrum?

IgA Explanation: IgA is primarily a secretory Ig that is found in saliva, tears, colostrum, and bronchial, gastrointestinal, prostatic, and vaginal secretions. Because it is found in secretions, its primary function is in local immunity on mucosal surfaces. IgA prevents the attachment of viruses and bacteria to epithelial cells.

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.

The nurse is reviewing the functions of immunoglobulins and determines which immunoglobulin is associated with its correct action?

IgM, the first antibody to be produced by a developing fetus. Explanation: The correct actions are as follows: IgM is the first circulating immunoglobulin that is produced by the developing fetus. It is instrumental in the ultimate lysis of microogranisms. It also is an effective agglutinating antibiody. IgA prevents the attachment of viruses and bacteria to epithelial cells. IgE is involved in inflammation, allergic responses, and combating parasitic infections. It binds to mast cells and basophils. IgD serves as an antigen receptor for initiating the differentiation of B cells.

A nurse is teaching a group of seniors about the decline of the immune system due to aging. Which topic should be included in the teaching plan regarding the immune response of older adults? Select all that apply.

Increase in susceptibility to infections Higher incidence of cancer Weakened response to vaccinations Explanation: As we age, the ability of the immune system to protect the body from pathogenic organisms and environmental toxins declines as a result of an overall decline in immune responsiveness. This results from changes in both cell-mediated and humoral immune responses. As a result, older adults are more susceptible to infections, have more evidence of autoimmune and immune complex disorders, and have a higher incidence of cancer than do younger people. In addition, the immune system of older adults is less likely to respond appropriately to immunization. As a result, older adults have a weakened response to vaccination. Older adults also frequently have many comorbid conditions that impair normal immune function and compromise the immune response.

A client is being treated for lupus, an autoimmune disease. The nurse is teaching the client how the immune system normally differentiates between self and non-self (foreign peptides). The nurse knows teaching has been effective when the client correctly identifies which molecule as the self-recognition protein?

Major histocompatibility complex (MHC) Explanation: The interaction between the cells of the immune system (B cell-T cell-APC) is restricted by the presence of cellular products genetically encoded by a self-recognition protein, called a major histocompatibility complex (MHC) molecule. This allows the lymphocyte to differentiate between self and foreign peptides.

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 pregnant client gets immunized for influenza while in the second trimester. What response occurs in the newborn after birth with regard to protection from the flu?

Maternal vaccination may offer fetal and neonatal passive immunity against the flu. Explanation: Maternal vaccination may offer fetal and neonatal passive immunity against common infections such as influenza.

Innate immunity, also called natural or native immunity, consists of mechanisms that respond specifically to which potential threat?

Microbes Explanation: Innate immunity is the first line of defense against microbial invasion and is in place before infection. Inflammation and antibody production are responses to microbes after they have invaded the body. The innate immune system is able to identify non-self-cells from self-cells.

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.

A teenager has been exposed to a person infected with chicken pox. After 2 weeks, the client has not contracted the virus. How is this possible? Select all that apply.

The client was vaccinated for chickenpox. The client was previously exposed to chickenpox. Explanation: Active immunity is acquired when the host mounts an immune response to an antigen either through the process of vaccination or from environmental exposure. It is called active immunity because it requires the host's own immune system to develop an immunologic response, including the development of memory. Passive immunity transferred from mother to fetus only lasts a few weeks to months following birth.

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.

A mother is diagnosed with a bacterial infection and is worried that her newborn infant will also contract the infection. Which statement should the nurse include in the teaching plan for the client?

Your newborn has maternal IgG antibodies that were transferred through the placenta before birth, providing some protection from infection. Explanation: Passive immunity is immunity transferred from another source. The most common form of passive immunity is that conferred from mother to fetus. During fetal development, maternal IgG antibodies are transferred to the fetus via the placenta. After birth, the neonate also 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.

The nurse is explaining the quality of pleiotropism that is possessed by many cytokines. The quality of pleiotropism implies that such cytokines:

are able to act on different types of cells. Explanation: Pleiotropism refers to the ability of a cytokine to act on different cell types. However, they cannot act on every type of cell and do not perform multiple functions on the same cell.

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.