14
Immune Responses and
Transplantation
Thuy Lynch, Yeow Chye Ng, and Haley Hoy
http://evolve.elsevier.com/Lewis/medsurg/
CONCEPTUAL FOCUS
Functional Ability Inflammation
Immunity Tissue Integrity
Infection
LEARNING OUTCOMES
1. Describe the components and functions of the immune 6. Describe the etiologic factors, clinical manifestations, and
system. treatment of autoimmune diseases.
2. Characterize the 5 types of immunoglobulins. 7. Discern the etiologic factors and categories of
3. Distinguish among the 4 types of hypersensitivity immunodeficiency disorders.
reactions in terms of immunologic mechanisms and 8. Explain the relationship between the human leukocyte
resulting alterations. antigen system and certain diseases.
4. Outline the clinical manifestations and emergency 9. Distinguish among the types of rejections after
management of a systemic anaphylactic reaction. transplantation.
5. Describe the assessment and interprofessional care of a 10. Identify the types and side effects of immunosuppressive
patient with chronic allergies. therapy.
KEY TERMS
anergy humoral immunity
antigen hypersensitivity reactions
autoimmunity immunocompetence
cell-mediated immunity immunodeficiency
cytokines immunosuppressive therapy
human leukocyte antigen (HLA)
Our bodies have several defense mechanisms for protecting
ourselves. One of the most complex is the immune response.
NORMAL IMMUNE RESPONSE
Immune processes must be functioning properly for the body Immunity is the body’s ability to resist disease. Immune
to defend itself against the presence of foreign substances. responses serve the following 3 functions:
This response is critical to maintaining health. Thus, many 1. Defense: The body protects against invasions by microorgan-
problems occur when the immune response is altered. These isms and prevents the development of infection by attacking
problems are closely related to the concepts of inflammation, foreign antigens and pathogens.
infection, and tissue integrity. You will find that the care of 2. Homeostasis: Damaged cellular substances are digested and
patients with immune disorders discussed in this chapter is removed. Through this mechanism, the body’s different cell
similar to the care of patients with inflammation (see Chapter types stay uniform and unchanged.
12), neutropenia (see Chapter 34), and general infection (see 3. Surveillance: Mutations continually arise. They are recog-
Chapter 15). nized as foreign cells and destroyed.
213
,214 SECTION 3 Problems Related to Homeostasis and Protection
Antigens Lymphoid Organs
An antigen is a substance that elicits an immune response. Most The lymphoid system is composed of central (or primary) and
antigens are composed of protein. However, other substances peripheral lymphoid organs. The central lymphoid organs are
such as large polysaccharides, lipoproteins, and nucleic acids the thymus gland and bone marrow. The peripheral lymphoid
can act as antigens. All the body’s cells have antigens on their organs are the lymph nodes; tonsils; spleen; and gut-, genital-,
surface. They are unique to that person and enable the body to bronchial-, and skin-associated lymphoid tissues (Fig. 14.1).
recognize itself. The immune system normally becomes “toler- We make lymphocytes in the bone marrow. They eventually
ant” to the body’s own molecules. This makes us nonresponsive migrate to the peripheral organs. The thymus is involved in the
to “self ” antigens. differentiation and maturation of T lymphocytes. This makes it
essential for a cell-mediated immune response. The thymus is
Types of Immunity its largest during childhood. After puberty, the thymus starts to
We classify immunity as innate or acquired. slowly shrink and become replaced by fat. By age 75, the thymus
is little more than fatty tissue and makes few T lymphocytes.
Innate Immunity When antigens enter the body, they may be carried by the
Innate immunity is present at birth. Its primary role is first-line bloodstream or lymph channels to regional lymph nodes. The
defense against pathogens. This type of immunity involves a antigens interact with B and T lymphocytes and macrophages
nonspecific response. Neutrophils and monocytes are the pri- in the lymph nodes. The 2 major functions of lymph nodes are
mary white blood cells (WBCs) involved. Innate immunity is (1) filtration of foreign material brought to the site and (2) cir-
not antigen specific. So, it can respond within minutes to an culation of lymphocytes.
invading pathogen without prior exposure to that organism. The tonsils are an example of lymphoid tissue. The spleen, a
peripheral lymph organ, is important as the primary site for fil-
Acquired Immunity tering foreign antigens from the blood. We have lymphoid tissue
Acquired immunity is the development of either active or passive in the submucosa of the GI (gut-associated), genitourinary (gen-
immunity (Table 14.1). ital-associated), and respiratory (bronchial-associated) tracts.
Active acquired immunity. Active acquired immunity This tissue protects the body from external microorganisms.
results from the invasion of the body by foreign substances The skin-associated lymph tissue consists primarily of lym-
such as microorganisms and the subsequent development of phocytes and Langerhans cells (type of dendritic cell) found in
antibodies and sensitized lymphocytes. With each reinvasion the epidermis of skin. When Langerhans cells are depleted, the
of the microorganisms, the body responds more rapidly and skin cannot initiate an immune response. Therefore, a delayed
vigorously to fight off the invader. Active acquired immunity hypersensitivity reaction (as determined by skin testing with
may result naturally from a disease or artificially through injected antigens) does not occur.
immunization. Because the body makes antibodies, immunity
takes time to develop but is long lasting.
Passive acquired immunity. In passive acquired immunity,
Tonsils
the host receives antibodies to an antigen rather than making Bronchial-
them. This may take place naturally through the transfer of associated
immunoglobulins across the placental membrane from mother lymphoid tissue
to fetus. Artificial passive acquired immunity occurs through
injection with gamma globulin (serum antibodies). The benefit
Skin-associated
of this immunity is its immediate effect. Unfortunately, passive Lymph nodes lymphoid tissue
immunity is short lived because the person does not make the
antibodies and memory cells for the antigen.
Thymus gland
TABLE 14.1 Types of Acquired Specific
Immunity
Type Natural Artificial
Active Natural contact with antigen Immunization with antigen Spleen
through actual infection (e.g., (e.g., vaccines for chicken-
chickenpox, measles, mumps) pox, measles, mumps)
Passive Transplacental and colostrum Injection of serum with Gut-associated
transfer from mother to child antibodies from 1 person lymphoid tissue
(e.g., maternal immunoglobulins (e.g., injection of hepatitis Bone marrow
passed to baby) B immune globulin) to Genital-associated
another person who does Lymph nodes lymphoid tissue
not have antibodies
Fig. 14.1 Organs of the immune system.
, CHAPTER 14 Immune Responses and Transplantation 215
Cells Involved in Immune Response B lymphocytes. B cells differentiate into plasma cells when
Mononuclear Phagocytes activated. Plasma cells make antibodies (immunoglobulins)
The mononuclear phagocyte system includes monocytes in (Table 14.2).
the blood and macrophages found throughout the body. T lymphocytes. Cells that migrate from the bone marrow to
Mononuclear phagocytes have a critical role in the immune sys- the thymus differentiate into T lymphocytes (thymus-dependent
tem. They are responsible for capturing, processing, and present- cells). The thymus secretes hormones, including thymosin, that
ing the antigen to the lymphocytes. This stimulates a humoral stimulate the maturation and differentiation of T lymphocytes.
or cell-mediated immune response. Capturing is accomplished T cells make up 70% to 80% of the circulating lymphocytes. They
through phagocytosis. The macrophage-bound antigen, which are mainly responsible for immunity to intracellular viruses,
is highly immunogenic, is presented to circulating T or B lym- tumor cells, and fungi. T cells can live from a few months to
phocytes and thus triggers an immune response (Fig. 14.2). the life span of a person. They account for long-term immunity.
We categorize T lymphocytes as T cytotoxic and T helper
Lymphocytes cells. Antigenic characteristics of WBCs can be classified using
We make lymphocytes in the bone marrow (Fig. 14.3). They monoclonal antibodies. These antigens are classified as clusters
then differentiate into B and T lymphocytes. of differentiation, or CD antigens. We refer to many types of
Body cells
G Memory T cells
A Virus Memory B cells
F
B Macrophage
E
Natural
killer cell
IL-1
TNF
Antibodies
C T helper cell
IL-2
T cytotoxic cells
IL-2 -IFN
B cells
D
Fig. 14.2 The immune response to a virus. (A) A virus invades the body through a break in the skin or another
portal of entry. The virus must make its way inside a cell to replicate itself. (B) A macrophage recognizes
the antigens on the surface of the virus. The macrophage digests the virus and displays pieces of the virus
(antigens) on its surface. (C) T helper cell recognizes the antigen displayed and binds to the macrophage.
This binding stimulates the production of cytokines (interleukin-1 [IL-1] and tumor necrosis factor [TNF]) by
the macrophage and interleukin-2 (IL-2) and γ-interferon (γ-IFN) by the T cell. These cytokines are intracel-
lular messengers that provide communication among the cells. (D) IL-2 instructs other T helper cells and T
cytotoxic cells to proliferate (multiply). T helper cells release cytokines, causing B cells to multiply and make
antibodies. (E) T cytotoxic cells and natural killer cells destroy infected body cells. (F) The antibodies bind to
the virus and mark it for macrophage destruction. (G) Memory B and T cells stay behind to respond quickly if
the same virus attacks again.
Immune Responses and
Transplantation
Thuy Lynch, Yeow Chye Ng, and Haley Hoy
http://evolve.elsevier.com/Lewis/medsurg/
CONCEPTUAL FOCUS
Functional Ability Inflammation
Immunity Tissue Integrity
Infection
LEARNING OUTCOMES
1. Describe the components and functions of the immune 6. Describe the etiologic factors, clinical manifestations, and
system. treatment of autoimmune diseases.
2. Characterize the 5 types of immunoglobulins. 7. Discern the etiologic factors and categories of
3. Distinguish among the 4 types of hypersensitivity immunodeficiency disorders.
reactions in terms of immunologic mechanisms and 8. Explain the relationship between the human leukocyte
resulting alterations. antigen system and certain diseases.
4. Outline the clinical manifestations and emergency 9. Distinguish among the types of rejections after
management of a systemic anaphylactic reaction. transplantation.
5. Describe the assessment and interprofessional care of a 10. Identify the types and side effects of immunosuppressive
patient with chronic allergies. therapy.
KEY TERMS
anergy humoral immunity
antigen hypersensitivity reactions
autoimmunity immunocompetence
cell-mediated immunity immunodeficiency
cytokines immunosuppressive therapy
human leukocyte antigen (HLA)
Our bodies have several defense mechanisms for protecting
ourselves. One of the most complex is the immune response.
NORMAL IMMUNE RESPONSE
Immune processes must be functioning properly for the body Immunity is the body’s ability to resist disease. Immune
to defend itself against the presence of foreign substances. responses serve the following 3 functions:
This response is critical to maintaining health. Thus, many 1. Defense: The body protects against invasions by microorgan-
problems occur when the immune response is altered. These isms and prevents the development of infection by attacking
problems are closely related to the concepts of inflammation, foreign antigens and pathogens.
infection, and tissue integrity. You will find that the care of 2. Homeostasis: Damaged cellular substances are digested and
patients with immune disorders discussed in this chapter is removed. Through this mechanism, the body’s different cell
similar to the care of patients with inflammation (see Chapter types stay uniform and unchanged.
12), neutropenia (see Chapter 34), and general infection (see 3. Surveillance: Mutations continually arise. They are recog-
Chapter 15). nized as foreign cells and destroyed.
213
,214 SECTION 3 Problems Related to Homeostasis and Protection
Antigens Lymphoid Organs
An antigen is a substance that elicits an immune response. Most The lymphoid system is composed of central (or primary) and
antigens are composed of protein. However, other substances peripheral lymphoid organs. The central lymphoid organs are
such as large polysaccharides, lipoproteins, and nucleic acids the thymus gland and bone marrow. The peripheral lymphoid
can act as antigens. All the body’s cells have antigens on their organs are the lymph nodes; tonsils; spleen; and gut-, genital-,
surface. They are unique to that person and enable the body to bronchial-, and skin-associated lymphoid tissues (Fig. 14.1).
recognize itself. The immune system normally becomes “toler- We make lymphocytes in the bone marrow. They eventually
ant” to the body’s own molecules. This makes us nonresponsive migrate to the peripheral organs. The thymus is involved in the
to “self ” antigens. differentiation and maturation of T lymphocytes. This makes it
essential for a cell-mediated immune response. The thymus is
Types of Immunity its largest during childhood. After puberty, the thymus starts to
We classify immunity as innate or acquired. slowly shrink and become replaced by fat. By age 75, the thymus
is little more than fatty tissue and makes few T lymphocytes.
Innate Immunity When antigens enter the body, they may be carried by the
Innate immunity is present at birth. Its primary role is first-line bloodstream or lymph channels to regional lymph nodes. The
defense against pathogens. This type of immunity involves a antigens interact with B and T lymphocytes and macrophages
nonspecific response. Neutrophils and monocytes are the pri- in the lymph nodes. The 2 major functions of lymph nodes are
mary white blood cells (WBCs) involved. Innate immunity is (1) filtration of foreign material brought to the site and (2) cir-
not antigen specific. So, it can respond within minutes to an culation of lymphocytes.
invading pathogen without prior exposure to that organism. The tonsils are an example of lymphoid tissue. The spleen, a
peripheral lymph organ, is important as the primary site for fil-
Acquired Immunity tering foreign antigens from the blood. We have lymphoid tissue
Acquired immunity is the development of either active or passive in the submucosa of the GI (gut-associated), genitourinary (gen-
immunity (Table 14.1). ital-associated), and respiratory (bronchial-associated) tracts.
Active acquired immunity. Active acquired immunity This tissue protects the body from external microorganisms.
results from the invasion of the body by foreign substances The skin-associated lymph tissue consists primarily of lym-
such as microorganisms and the subsequent development of phocytes and Langerhans cells (type of dendritic cell) found in
antibodies and sensitized lymphocytes. With each reinvasion the epidermis of skin. When Langerhans cells are depleted, the
of the microorganisms, the body responds more rapidly and skin cannot initiate an immune response. Therefore, a delayed
vigorously to fight off the invader. Active acquired immunity hypersensitivity reaction (as determined by skin testing with
may result naturally from a disease or artificially through injected antigens) does not occur.
immunization. Because the body makes antibodies, immunity
takes time to develop but is long lasting.
Passive acquired immunity. In passive acquired immunity,
Tonsils
the host receives antibodies to an antigen rather than making Bronchial-
them. This may take place naturally through the transfer of associated
immunoglobulins across the placental membrane from mother lymphoid tissue
to fetus. Artificial passive acquired immunity occurs through
injection with gamma globulin (serum antibodies). The benefit
Skin-associated
of this immunity is its immediate effect. Unfortunately, passive Lymph nodes lymphoid tissue
immunity is short lived because the person does not make the
antibodies and memory cells for the antigen.
Thymus gland
TABLE 14.1 Types of Acquired Specific
Immunity
Type Natural Artificial
Active Natural contact with antigen Immunization with antigen Spleen
through actual infection (e.g., (e.g., vaccines for chicken-
chickenpox, measles, mumps) pox, measles, mumps)
Passive Transplacental and colostrum Injection of serum with Gut-associated
transfer from mother to child antibodies from 1 person lymphoid tissue
(e.g., maternal immunoglobulins (e.g., injection of hepatitis Bone marrow
passed to baby) B immune globulin) to Genital-associated
another person who does Lymph nodes lymphoid tissue
not have antibodies
Fig. 14.1 Organs of the immune system.
, CHAPTER 14 Immune Responses and Transplantation 215
Cells Involved in Immune Response B lymphocytes. B cells differentiate into plasma cells when
Mononuclear Phagocytes activated. Plasma cells make antibodies (immunoglobulins)
The mononuclear phagocyte system includes monocytes in (Table 14.2).
the blood and macrophages found throughout the body. T lymphocytes. Cells that migrate from the bone marrow to
Mononuclear phagocytes have a critical role in the immune sys- the thymus differentiate into T lymphocytes (thymus-dependent
tem. They are responsible for capturing, processing, and present- cells). The thymus secretes hormones, including thymosin, that
ing the antigen to the lymphocytes. This stimulates a humoral stimulate the maturation and differentiation of T lymphocytes.
or cell-mediated immune response. Capturing is accomplished T cells make up 70% to 80% of the circulating lymphocytes. They
through phagocytosis. The macrophage-bound antigen, which are mainly responsible for immunity to intracellular viruses,
is highly immunogenic, is presented to circulating T or B lym- tumor cells, and fungi. T cells can live from a few months to
phocytes and thus triggers an immune response (Fig. 14.2). the life span of a person. They account for long-term immunity.
We categorize T lymphocytes as T cytotoxic and T helper
Lymphocytes cells. Antigenic characteristics of WBCs can be classified using
We make lymphocytes in the bone marrow (Fig. 14.3). They monoclonal antibodies. These antigens are classified as clusters
then differentiate into B and T lymphocytes. of differentiation, or CD antigens. We refer to many types of
Body cells
G Memory T cells
A Virus Memory B cells
F
B Macrophage
E
Natural
killer cell
IL-1
TNF
Antibodies
C T helper cell
IL-2
T cytotoxic cells
IL-2 -IFN
B cells
D
Fig. 14.2 The immune response to a virus. (A) A virus invades the body through a break in the skin or another
portal of entry. The virus must make its way inside a cell to replicate itself. (B) A macrophage recognizes
the antigens on the surface of the virus. The macrophage digests the virus and displays pieces of the virus
(antigens) on its surface. (C) T helper cell recognizes the antigen displayed and binds to the macrophage.
This binding stimulates the production of cytokines (interleukin-1 [IL-1] and tumor necrosis factor [TNF]) by
the macrophage and interleukin-2 (IL-2) and γ-interferon (γ-IFN) by the T cell. These cytokines are intracel-
lular messengers that provide communication among the cells. (D) IL-2 instructs other T helper cells and T
cytotoxic cells to proliferate (multiply). T helper cells release cytokines, causing B cells to multiply and make
antibodies. (E) T cytotoxic cells and natural killer cells destroy infected body cells. (F) The antibodies bind to
the virus and mark it for macrophage destruction. (G) Memory B and T cells stay behind to respond quickly if
the same virus attacks again.
