Unit 3 Disturbances of the Immune System
UNIT 3
Disturbances of the Immune
System
James A. Rankin RN, PhD
Associate Professor
Faculty of Nursing
University of Calgary
1
Unit 3 Table of Contents
Overview ..............................................................................................................4
Aim .................................................................................................................... 4
Objectives ......................................................................................................... 4
Orientation to the Unit ................................................................................... 4
Resources .......................................................................................................... 5
Web Links......................................................................................................... 5
Section 1: The Normal Immune Response .....................................................6
Immune Responses ......................................................................................... 7
For Your Interest ........................................................................................... 10
Section 2: Aquired Immune Deficiency Syndrome (AIDS) .....................15
Etiology........................................................................................................... 15
Prevalence ...................................................................................................... 16
Populations at Risk ....................................................................................... 17
Pathogenesis .................................................................................................. 18
Modes of Transmission ................................................................................ 19
Clinical Manifestations ................................................................................. 20
Surveillance .................................................................................................... 20
Prognosis and Trajectory ............................................................................. 22
Learning Activity #1 ..................................................................................... 23
Study Questions ............................................................................................ 24
Section 3: Immunodeficiency .........................................................................25
Phagocytosis .................................................................................................. 25
Complement .................................................................................................. 25
Hypersensitivity ............................................................................................ 26
Autoimmune Linked Disease ...................................................................... 27
References ..........................................................................................................28
Glossary ..............................................................................................................30
Acronym List ......................................................................................................30
Checklist of Requirements..............................................................................30
Answers to Learning Activities ......................................................................30
Learning Activity #1 ..................................................................................... 30
Unit 3 Disturbances of the Immune System
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UNIT 3
Disturbances of the Immune System
Advances in technology and molecular biology in the late eighties, have
led to a dramatic increase in knowledge with respect to the immune
system (Gallo & Montagnier, 1988). The research effort that is directed
towards understanding the Human Immunodeficiency Viruses (HIV)
has succeeded in advancing this knowledge base. While it is perhaps
true that the Acquired Immune Deficiency Syndrome (AIDS) epidemic
has brought the science of immunology to the fore, not only to health
professionals but also to the public at large, it is important to note that
AIDS represents one example of many conditions in which the immune
system is involved. You will quickly realize as you proceed through the
pathophysiology units that there are in fact very few diseases about
which we know the etiology. For example the immune system is
implicated to a greater or lesser extent with certain cancers, ulcerative
colitis, Crohn’s disease, multiple sclerosis and rheumatoid arthritis to
name a few.
In recent years researchers have identified strong links between the
immune system and the nervous system. It would appear that one
system can be affected by the other. In addition it has been suggested
that the individual is capable of influencing the immune system at a
conscious level (Solomon, 1987; Petrie et al., 1999). That is, we can
suppress or enhance the response of the system consciously!
Researchers have also found that the endocrine system is involved too.
The name given to the science that has emerged is
psychoneuroimmunoendocrinology (usually shortened to
psychoneuroimmunology!). For further reading on this fascinating area
you might wish to look at Blalock (1984); Plant & Friedman (1981); Ader
(1981); Solomon & Moos (1964). Please note that these additional
readings are for interest only, the material contained within them will
NOT be tested.
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Unit 3 Disturbances of the Immune System
Overview
Aim
The aim of this unit is to increase your knowledge of the immune
system and the normal immune response. You will then be expected to
use this knowledge to facilitate your understanding of various
disorders resulting from immune system dysfunction
Objectives
On completion of this unit you will be able to:
1. Describe the mechanisms involved in the normal immune
response.
2. Describe the B and T cell lines.
3. Discuss the etiology and pathophysiology of Acquired Immune
Deficiency Syndrome (AIDS).
4. Briefly describe the mechanisms involved in auto-immune
linked diseases (e.g., systemic lupus erythematosus, rheumatoid
arthritis).
5. Relate your knowledge of the immune response to certain
immunodeficiency and hypersensitivity states.
Orientation to the Unit
This is a fairly heavy unit; you may want to divide it into sections and
take your time with each section. For example, the readings could
constitute one section, then the normal immune system, AIDS, and
finally immunodeficiency states. I would strongly recommend that you
do not attempt this unit in one “sitting”. I would also recommend that
you work through this unit with the course textbook (Porth, 2005.
Chapter 19 ) right beside you as I refer to it as you work through the
unit.
In order to complete this unit it is recommended that you do the
required readings listed below. In addition you may wish to brush up
on your knowledge of the immune system by reading an appropriate
anatomy and physiology text.
In the previous unit on wound healing, you already studied some of the
principles and processes involved in the non-specific immune response
(i.e. inflammation). In this unit you will build on and expand that
knowledge.
Rankin, Reimer & Then. © 2000 revised edition. NURS 461 Pathophysiology, University of Calgary
Unit 3 Disturbances of the Immune System
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Resources
Requirements Porth, C. M. (2005). Pathophysiology –
Concepts in Altered Health States (7th ed). Philadelphia:
Lippincott.
Web Links
All web links in this unit can be accessed through the Web CT system.
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Unit 3 Disturbances of the Immune System
Section 1: The Normal Immune Response
As previously discussed in the Wound Healing unit, the inflammatory
response is mounted within seconds of being stimulated either by
injury or invasion by an antigen. One of the features of the
inflammatory response is that it is nonspecific. What does “nonspecific”
mean? This is perhaps best answered with respect to the immune
response which is specific. Before looking at this it is important to
understand what an antigen is. Essentially an antigen is any substance
capable of stimulating an antibody response. There are a number of
characteristics of the immune response including:

Specificity—This refers to the ability of certain cells of the
immune system to produce an antibody that is specific to a
particular antigen. When a host is invaded by an antigen, for
example the streptococcus bacterium, not just any antibodies are
produced. The antibodies are specific to the streptococcus and
are capable of dealing with it in a number of ways.

Memory—This is an interesting property of the immune system
and provides the basis for vaccine therapy. When a host is
exposed to an antigen, an antibody response is mounted (the
primary response). On subsequent exposure at a different time
to the same antigen, a rapid and large antibody response (the
secondary or anamnestic response) is seen. This secondary
response is due to cells known as memory cells. Can you see
how this property relates to vaccine therapy?

Self and Non-self—A healthy immune system has the ability to
recognize those cells that belong to the host as “self” and any
other cells as “non-self”. Any time that the host is invaded by an
antigen the immune system recognizes this as “foreign” (or nonself) and therefore mounts a response to this. This is of course a
protective defense mechanism. This property works against us
in the case of organ transplantation. The immune system does
not “know” that a transplanted organ has been put there for
beneficial purposes and so it recognizes it as foreign and attacks.
Hence, people with organ transplants require
immunosuppressive drugs to prevent the immune system from
doing its job! When the immune system (for some reason)
breaks down it can start to attack its own host cells. This is what
appears to happen in auto-immune linked diseases, (Greek, auto
= self). This is dealt with later in the unit.

Hypersensitivity—This will be dealt with later in the unit too.
Suffice to say at this point, that this is an extremely abnormal
Rankin, Reimer & Then. © 2000 revised edition. NURS 461 Pathophysiology, University of Calgary
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immune response which rather than contributing to recovery
can actually produce tissue damage.
Immune Responses
Four types of immune responses have been identified.
1. The Humoral Response or humoral antibody response, as the
latter name implies, involves the production of antibodies.
Another name for antibodies is “immunoglobulins,” this is
commonly abbreviated to Ig. There are five classes of
immunoglobulins: IgA; IgD; IgE; IgG and IgM. The Ig’s enter the
bloodstream (and other areas) and combine with antigens to
form an antigen-antibody complex (or immune complex) which
is capable of destroying the antigen by various means.
2. Cell Mediated Immunity (CMI)—Cell mediated immunity is
carried out by the T lymphocytes. The T lymphocytes are
capable of “recognizing” antigens and directly attacking and
neutralizing them. The immunity is carried out by cells of the
immune system rather than antibodies, hence the immunity is
cell mediated.
3. Phagocytosis
4. Complement Response, each of these will be dealt with later in
the unit.
The immune system consists of many different types of cells which
interact with one another in establishing an immune response. It is not
necessary to memorize all the types of cells involved, it is better to try
and gain an understanding of the system in general.
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Unit 3 Disturbances of the Immune System
Overview of the Immune System
The generic name for cells of the immune system is “white blood cells”,
or LEUCOCYTES (leuco/leuko = white; cyte = cell).
There are five cell types:
1.
2.
3.
4.
5.
neutrophils
eosinophils
basophils
monocytes
lymphocytes
These are
collectively known
as granulocytes
There are two lymphocyte cell lines:
Humoral Response
Cell Mediated Immunity
B cells

“BURSA”

PLASMA CELL

IgM IgA IgG
IgD IgE

Memory cells
Humoral response—against bacterial
infection (e.g., staphylococci,
pneumococci)
T cells

THYMUS

MATURE T CELL

T cells differentiate into:
killers, memory, helpers,
suppressors, lymphokine producers

CMI response—against viruses,
intracellular bacteria, fungi, graft
rejection immunological surveillance
(e.g., destroys neoplastic cells)
The B cells are so called because early research in birds demonstrated
the existence of an organ in the gastrointestinal tract called a “bursa,”
the removal of which meant that the bird’s humoral response was
eliminated. A bursa has not been demonstrated in humans, however it
is believed that the bone marrow is the site of maturation of B cells,
hence it is known as the “bursa equivalent.”
The T cells on the other hand derive their name from the fact that they
go through a maturation process in the thymus gland. The thymus
(please note it is thymus and not thyroid) gland occupies a space in the
mediastinum. The thymus is active until puberty and then it atrophies.
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Note: the textbook states that the cells that leave the thymus are
“immature.” This should be interpreted as “inactive.”
In summary then, the B cells are lymphocytes that are responsible for
humoral antibody response. They differentiate into plasma cells and the
plasma cells synthesize large amounts of antibodies
(immunoglobulins). The Ig’s are specific to the invading antigen.
Memory B cells are responsible for mounting the secondary
(anamnestic) response when the host is invaded by the same antigen at
a different point in time. The humoral response defends the host against
extracellular bacterial infection.
The T cells are lymphocytes that are responsible for cell mediated
immunity (CMI). T cells mature in the thymus gland and can
differentiate into different cell types. The CMI defends the host against
viruses, intracellular bacteria, fungi and, is responsible for graft
rejection and immunological surveillance. ALL of the cells of the
immune system take part in the overall immune response.
Stop for a break! This next section is not necessary for exam purposes.
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Unit 3 Disturbances of the Immune System
For Your Interest
Before looking at AIDS you might be interested in knowing how your
immune system recognizes itself?
If you are not interested in this, then skip to the next part of the unit
that deals with AIDS. The following content is NOT on the exam so it is
quite safe to skip it if you wish. (Honest! — Trust me, I’m a nurse).
How does your immune system recognize you? Well the answer to that
is all in your genes!
1. First of all, a major group of genes have been identified. The
genes have been found on four loci (Latin, loci = places) on the
short arm of chromosome number 6 (See Figure 3.1 for an
overview).
Figure 3.1 Overview of major histocompatibility complex on
chromosome 6
2. These genes code for proteins (as most genes do) and the
proteins that they code end up on the cell surface of most cells of
your body. To get a handle on this you have to try and think at a
microscopic level. We (in our MACROscopic world) tend to
think of cells as flat round things we see in biology textbooks.
However, the advent of the electron microscope and the
photographs we can get from it (known as electron
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Unit 3 Disturbances of the Immune System
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micrographs) has helped us to try and visualize cells as three
dimensional . So we have to think of the cell as a three
dimensional object with a cell surface that is not nice and
smooth but rather full of lumps, bumps, flagpoles and holes!
3. Back to the proteins on the cell surface (the flagpoles)—The
proteins are known as:



histocompatibility antigens OR
HLA antigens OR
HLA determinants
These names all
refer to the same
things
By now you may have some questions you want to ask. Let me see if I
can anticipate some them:
a.
b.
c.
d.
Why are the proteins called histocompatibility antigens?
Why are the proteins called HLA antigens?
Why are the proteins called antigens?
Why are the proteins called HLA determinants?
Answers:
a. The proteins are called histocompatibility antigens because
the area on the chromosome where the genes that code for
the proteins are found, is known as the major
histocompatibility complex (or MHC). (See Figure 3.2 on the
next page)
b. The proteins are known as HLA antigens because a scientist
called Dausset found the proteins on Human Leucocyte
(system) A, in 1954.
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Unit 3 Disturbances of the Immune System
Figure 3.2 The major histocompatibility complex on chromosome 6
c. The proteins are called antigens because they would act as
antigens (i.e. stimulate the immune response) if they were
found in someone else’s body. In other words, if you had to
get one of my kidneys (I can’t think why you would want
it!), then the proteins (or antigens) on the surface of my
kidney cells would signal (remember the flagpoles) your
immune system. Your immune system would spring into
action and “know” immediately that this was not your
kidney!
d. They are called HLA determinants because the cell surface
proteins help determine the different types of cells.
4. Remember I said that the area on the chromosome where the
genes are found is known as the major histocompatibility
complex? Well the area is also known as the HLA complex. Can
you see why from the above information? If not, read over part 3
again. Remember the 4 loci (places) on the chromosome? These
represent four areas on the MHC where the genes are located
and they are designated A, B, C and D/DR. The proteins (or
antigens) that are coded by the genes are divided into two
classes. The proteins from loci A, B, and C are known as class I
antigens. Most cells have these, except for red blood cells, they
have their own (about 80 or so). The proteins from locus (note:
loci, plural; locus, singular) D/DR are known as class II antigens
and they are mostly found on B lymphocytes. (See Figure 3.3)
Rankin, Reimer & Then. © 2000 revised edition. NURS 461 Pathophysiology, University of Calgary
Unit 3 Disturbances of the Immune System
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Figure 3.3 The four gene loci (A, B, C and D/DR) on the major
histocompatibility complex
In summary your immune system recognizes you because:







There are genes located on the short arm of Chromosome 6
On the short arm there is an area called the Major
Histocompatibility Complex (MHC)
There are four places (loci) on the MHC designated A, B, C and
D/DR
At these loci genes are found that code for proteins (also known
as antigens -- HLA antigens)
The genes at loci A, B, and C code for Class I antigens -- most
cells have these except red blood cells
The genes at locus D/DR code for Class II antigens --found
mostly on lymphocytes
The antigens act as cell surface markers (flagpoles). This allows
for self and non-self distinction by the immune system.
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Unit 3 Disturbances of the Immune System
Figure 3.4 Cell surface markers and self and non-self distinction by the
immune system
In Figure 3.4, above the cell surface, markers (the flagpoles) allow the
immune system (in this case a macrophage) to recognize that the cell is
not foreign.
5. Quite apart from the kidney transplant story above, the HLA
antigens (= histocompatibility antigens = HLA determinants =
proteins = cell surface flagpoles) are also involved in tissue to
tissue distinction within the same individual.
6. The quality and quantity of the immune response is in part
controlled by genes in the HLA (MHC) complex. They are
known as immune response or Ir genes.
If you are interested in reading more about the immune system I would
recommend the book by Michael Taussig listed in the references.
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Unit 3 Disturbances of the Immune System
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Section 2: Aquired Immune Deficiency
Syndrome (AIDS)
Before we begin—a word of advice:
Acquired immune deficiency syndrome is thought of as a fairly "new"
infectious disease. It is one that has received huge amounts of media
attention and sensationalism as well as widespread interest among
health care workers and researchers. Due to the vast amount of research
that is being done it seems as though new knowledge about the disease
is being discovered almost daily. Thus any document concerning AIDS
can quickly become outdated and this particular unit is no exception. It
is your professional responsibility to keep your knowledge current
especially in an area where there is rapid turnover of research findings.
While newspaper reports may be entertaining, very few are informative
to the level required for professional practice. It behooves us as health
care professionals to obtain our knowledge from respectable scientific
journals and textbooks and we have to be extremely cautious in the way
that we interpret reports from the mass media.
Etiology
Between October 1980 and May 1981, five cases of Pneumocystis carinii
pneumonia were reported in young and otherwise healthy homosexual
males in Los Angeles (Centers for Disease Control, 1981).
This was unusual as this type of pneumonia had only occurred before
in older patients who were immunosuppressed. In addition, in early
1981 a larger than usual number of cases of Kaposi’s sarcoma was seen
in young homosexual males (Centers for Disease Control, 1981). This
was of note because this type of cancer was almost always seen in
elderly people (both males and females).
The Centers for Disease Control initiated a surveillance program as it
was believed that what was being seen was the emergence of a new
disease.

1983 Montagnier and his co-workers at the Pasteur Institute in
Paris isolate a new virus from the swollen lymph glands of a
patient. It is named Lymphadenopathy Associated Virus (LAV).

1984 Gallo and his co-workers in the US perform a detailed
study of a new virus. It is named Human T cell Lymphotropic
Virus type III (HTLV type III).
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Unit 3 Disturbances of the Immune System
It was later discovered that both LAV and HTLV III viruses were the
same. By international agreement the virus is now known as the
Human Immunodeficiency Virus (HIV). To date two viruses have been
identified, HIV I and HIV II. It would appear that HIV II is more
prevalent in certain parts of Africa, in particular West Africa, whereas
HIV I is more common in North America. It is important to note that
both HIV I and HIV II can cause AIDS.
It is also important to note that an HIV infected individual may or may
not have AIDS. Infection by the HIV virus may cause a progressive
dysfunction of the immune system; the disease known as AIDS is a late
(or end stage) manifestation of this process (Redfield & Burke, 1988).
Other important points:

Being HIV positive means that the infected individual has raised
sufficient antibody levels in the blood that can be detected on
screening. It is more correct to say that an individual is HIV
antibody positive.

An individual may be infected with the virus and not be HIV
antibody positive on testing. This is because it may take
anywhere from a few weeks to a few months for that individual
to raise a sufficient antibody titre i.e. seroconvert.

Initially it was thought that those individuals who were HIV
antibody positive went on to develop AIDS within 2 years of
being infected. This incubation period was extended to 5 years,
currently it is thought that it may be 30 years or more. This has
obvious implications for the spread of the disease. Anyone who
is HIV antibody positive is capable of transmitting the virus,
and of course, infecting others.
Prevalence
Strictly speaking, the prevalence of a disease indicates the number of
individuals in a population who have a disease at a particular point in
time. The incidence, quantifies the number of new cases that develop in
a population in a given time period. This time period is usually one
year, however in the case of AIDS it is not uncommon to see monthly or
six monthly statistics.
As of November 30, 1988 a total of 139,886 cases of AIDS had been
reported to the World Health Organization (WHO), (AIDS Information,
1989). However, there have been difficulties with recognition, diagnosis
and reporting, especially in the developing countries. It is estimated by
WHO that there may be more than 200,000 cases of AIDS worldwide
and that between 5-10 million people are infected with HIV (Mann,
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Unit 3 Disturbances of the Immune System
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Chin, Piot & Quinn, 1988). More recently, projections from WHO (WHO
web site, 2000) suggest that 3.4 million adults and children are living
with HIV/AIDS worldwide. The largest number infected live in subSaharan Africa (24.5 million).
Other points:



In North America high HIV infection rates are found among:
o homosexual and bisexual males
o people with haemophilia
o intravenous drug abusers
o children born to infected mothers
o heterosexual partners of infected persons
Males have higher prevalence than females
Higher prevalence rates have been recorded in persons between
20 to 45 years of age
In Africa the prevalence picture is quite different:




Females are equally infected as males
Transmission of the virus by homosexual activity or intravenous
drug abuse is low or absent
Perinatal transmission is common
HIV II is more prevalent than HIV I
It is important to note that HIV infection and therefore AIDS does not
only occur in those men or women who engage in homosexual
practices. Anyone can be infected and therefore anyone can get AIDS.
Populations at Risk
The HIV is transmitted by three main routes: by contaminated blood,
sexual contact with infected semen, and
intrauterine/peripartum/postpartum exposure to infected body fluids
(blood, breast milk) (Friendland & Klein, 1988).
Populations at risk are therefore those who:
1. Are exposed to contaminated blood by virtue of their lifestyles
(intravenous drug users), by specific disorders (hemophiliacs),
and by situational incidents (transfusion recipients).
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Unit 3 Disturbances of the Immune System
2. Are exposed to contaminated semen (homosexual/bisexual
men, sexual partners of intravenous drug users, and anyone
engaging in unprotected sexual activity with a partner/partners
whose antibody status is unknown).
3. Are children of infected mothers. Children can become infected
in utero (transplacental transmission), during birth (blood to
blood transmission) or after birth (breast milk). However,
unless clinical manifestations of AIDS present in these children,
it is impossible to decide their antibody status until
approximately 18 months after birth since HIV antibodies are
transmitted from mother to child regardless of whether the child
is infected or not (Giaguinto, DeRossi & Laverda, 1988).
HIV has been isolated from blood, semen, vaginal secretions, saliva,
tears, breast milk, urine, serum, cerebrospinal fluid, and alveolar fluid.
Only blood, semen, breast milk and vaginal fluids have been directly
implicated in transmission.
Pathogenesis
Main points:




HIV is a lentevirus which belongs to the family of retroviruses.
Retroviruses carry their genetic information in ribonucleic acid
(RNA) rather than deoxyribonucleic acid (DNA).
The main target in HIV infection is T4 helper cells. (You will
recall that helpers are a subset of the T lymphocyte line).
Briefly the process is as follows:
o HIV gains access to the blood of the host.
o HIV binds to T4 helpers.
o The virus binds to the T4 cells with the help of a receptor
molecule known as CD4. CD4 is a cell surface protein (or
antigen) found on T4 helper cells (we discussed flagpoles in
the section on immune recognition)
o HIV contains an enzyme, reverse transcriptase, which allows
the RNA to be transcribed into DNA.
o Some of the DNA is incorporated into the T4 cell’s own
DNA.
o Replication of the viral DNA may now take place. In other
words the viral DNA can instruct the T4 cell to make more
viruses!
o The viral DNA may lie dormant in the T4 cell. The stimulus
to turn on the DNA is not known. Hence an individual may
be infected with the virus but for some reason his T4 cells
have not been instructed to make more viruses. When the
Rankin, Reimer & Then. © 2000 revised edition. NURS 461 Pathophysiology, University of Calgary
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instruction is given and vast amounts of virus is produced
the individual goes on to develop AIDS.
The virus is replicated, lyses the T4 cell and goes on to infect
other T4 cells and other cells of the immune system e.g.
monocytes. Monocytes can cross the blood-brain barrier. It is
thought that the virus gains access to the CSF and the brain
tissue by being transported across the blood-brain barrier in
the monocytes.
You will recall that the humoral response is mounted by the B cells
(antibody production) and the T lymphocytes (especially the killers) are
responsible for cell mediated immunity. Both of these responses are
coordinated and organized by the T4 helper cells. In other words the
very cells that are designed to orchestrate the humoral and CMI
responses are the prime targets for the virus!
Thus the virus is not just responsible for infecting the T4 helpers but
also for indirectly “knocking out” the individual’s capability of
mounting an immune response. This leaves the host susceptible to:



All forms of infection (viral, bacterial, fungal, protozoan)
No immunological surveillance—hence neoplasms develop
No immunological “memory”—hence infections which would
otherwise be controlled can become established (opportunistic
infections)
Modes of Transmission
From the preceding discussion and from your readings you probably
are aware of the modes of transmission of the virus:




Sexual intercourse—especially receptive anal intercourse
Parenteral
o IV drug abuse
o Blood and blood products (e.g. whole blood, plasma, cellular
components and clotting factors)
Transplacental
The virus has also been isolated in a number of body fluids (e.g.,
tears, saliva and breast milk)
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Unit 3 Disturbances of the Immune System
Clinical Manifestations
Evaluation and Treatment
In the absence of a cure for AIDS, patient management is focused on
treating the various disorders resulting from the immune system
dysfunction. A variety of therapies for the infections and malignancies
commonly encountered in AIDS patients already exist while
development of new ones is rapidly underway. However, due to the
current impossibility of eliminating the virus or halting viral
replication, the disease course is characterized by recurrent
overwhelming infections and cancers which ultimately result in the
patient’s death.
Nursing management of AIDS patients includes interdependent and
independent nursing functions. Interdependent functions include
administration of medications, oxygen and intravenous fluids. Diligent
observation and assessment of the patient’s responses to the prescribed
therapeutic regimen are important nursing functions. Independent
nursing interventions include maintaining nutritional status, comfort
measures, patient education, skin and mouth care and psychosocial
support.
AIDS is a fatal disease which has a profound effect on all aspects of an
individual’s life. The primary objective of nursing care is to assist the
patient in meeting all of his biopsychosocial needs and strive to increase
quality of life by providing holistic, compassionate nursing care.
text for treatment, prevention and evaluation information.
Surveillance
The Centers for Disease Control expanded the case definition for AIDS
in 1995 to include:

All human HIV infected adults and teens (who are 13 yrs or
older) who have either:
o  200 CD4 + T lymphocytes/ul
o  14% CD4 + T cells relative to total lymphocyte count

Any of the following 3 clinical conditions (including HIV
infection)
o pulmonary TB
o recurrent pneumonia, or
o invasive cervical cancer
Or
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The expanded case definition still contains the 23 other clinical
conditions in the 1987 AIDS surveillance definition (Centers for Disease
Control, 1992).
Comprehensive, ongoing assessment of patients’ responses to treatment
and overall status includes monitoring of T4 cell count in peripheral
blood. T4 count below 400 cells/mm3 indicates profound immune
system dysfunction and imminent danger of infections which very
quickly can become life threatening. Arterial blood gases, hemoglobin
levels, and granulocyte counts provide important information about
oxygenation of blood, phagocytic potential in the presence of bacterial
infections and the competency level of the bone marrow. Parameters
such as blood albumin and blood urea nitrogen (BUN) provide the
nurse with important information about the patient’s nutritional status.
Frequent assessment of the neuropsychiatric status can lead to early
detection of debilitating, life-threatening CNS infections.
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Unit 3 Disturbances of the Immune System
Prognosis and Trajectory
Following infection by the HIV, some individuals develop flu-like
symptoms (low-grade fever, muscle weakness, fatigue). It is currently
unknown whether all HIV seropositive individuals go on to develop
AIDS but the time period between infection and onset of AIDS has been
reported to be a long as 8-9 years and may be as long as 20 years or
more. Development of symptoms such as lymphadenopathy, fatigue,
fever, weight loss, night sweats and diarrhea marks the beginning of
what is now know as HIV disease (formerly AIDS-related complex or
ARC). When infections and cancers listed in the CDC (1987) case
definition of AIDS develop, the individual has reached the last phase in
the spectrum of HIV infection. The fatality rate of AIDS is 100% (Mann,
Chin, Piot & Quinn, 1988). In the US between 80-90% of people with
AIDS diagnosed before 1986 have already died (Heyward & Curran,
1988).
More information can be obtained from:


Centers for Disease Control (1994). Revised classification system
for human immunodeficiency varus infection in children less
than 13 years of age. Morbidity & Mortality Weekly Report. (No.
RR-12).
Also the following websites:
Centers for Disease Control and Prevention
http://www.cdc.gov/epo/mmwr/other/case_def/aids97.html
University of California San Francisco HIV Insight
http://hivinsite.ucsf.edu/akb/1997/o1class/index.html
Rankin, Reimer & Then. © 2000 revised edition. NURS 461 Pathophysiology, University of Calgary
Unit 3 Disturbances of the Immune System
23
Learning Activity #1
Here is a quick quiz on AIDS (answers at the end of the section).
Based on your reading, complete the following questions:
1. The cause of AIDS is:
a. pneumocystic carinii
b. human immunodeficiency virus
c. human herpes virus 6
d. unknown
2. AIDS is characterized by a breakdown in:
a. the humoral immune response
b. the inflammation process
c. the cell-mediated immune response
d. macrophage activity
3. The cell type most profoundly depleted in AIDS is:
a. B-cells
b. macrophages
c. T4 cells
d. T8 cells
4. The opportunistic infection most commonly encountered in
people with AIDS is:
a. Pneumocystis carinii pneumonia
b. Cryptosporidium
c. Toxoplasmosis
d. Salmonella
5. The cancer most commonly encountered in people with AIDS is:
a. Testicular cancer
b. Lymphoma
c. Kaposi’s sarcoma
d. colorectal cancer
6. AIDS has never been diagnosed in individuals belonging to
which of the following groups:
a. school children
b. homosexual men
c. intravenous drug users
d. women of childbearing age
e. none of the above
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Unit 3 Disturbances of the Immune System
7. Infection by the etiologic agents in AIDS can be transmitted by:
a. semen only
b. semen, blood, breast milk
c. semen, blood, tears
d. casual contact
Study Questions
The following questions are provided to help you synthesize the
information you have obtained from your readings. It is highly
recommended that you work on these in small groups.
1. A young woman has recently been diagnosed with AIDS. She
has some questions about the cause and disease trajectory. How
would you go about giving her the information?
2. A group of adolescents approach you with questions about
AIDS. They specifically want to know how it is transmitted and
how they can avoid the infection. What would you tell them?
3. An AIDS patient suffering from recurrent episodes of
pneumocystic carinii pneumonia asks you for the reason behind
this particular condition. What is your answer?
Rankin, Reimer & Then. © 2000 revised edition. NURS 461 Pathophysiology, University of Calgary
Unit 3 Disturbances of the Immune System
25
Section 3: Immunodeficiency
Immunodeficiency may be viewed as a diminished capability of the
immune system to mount an immune response. The immune system
may be diminished either in quantity or quality.
You will recall the four types of immune response mentioned earlier:
1.
2.
3.
4.
Humoral antibody response
Cell mediated immunity (CMI)
Phagocytosis
Complement
The first two listed above have been described. Let’s take a look at the
other two.
Phagocytosis
Phagocytosis is a function of the neutrophils and macrophages. These
cells are attracted to a site of inflammation and essentially ingest and
destroy the invading organism.
Complement
The biochemical and immunological complexity of the complement
system is beyond the scope of this unit, therefore only a brief overview
will be given here.
Complement is a plasma protein system consisting of a sequence of 9
proteins (C1 to C9The proteins are normally present in an inactive form,
and their actions are closely involved with the inflammatory and the
immune response. Complement may be activated by plasmin and
thrombin. Both of these substances are present in acute inflammation.
Enzymes that are released from dead neutrophils (i.e. after
phagocytosis) may also activate complement.
The complement system enhances the inflammatory response by:

opsonization of bacteria—this makes it easier for neutrophils
and macrophages to phagocytose
 attracting neutrophils to the site of inflammation by the use of
chemical mediators—this process is known as chemotaxis
 increasing vasodilation and permeability at the site of
inflammation
In immunodeficiency states one or more of these immune mechanisms
may be involved. Immunodeficiency states may be classified as:

primary immunodeficiency (hereditary or congenital)
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Unit 3 Disturbances of the Immune System

secondary immunodeficiency (acquired after birth)
Some Examples:
1. Secondary humoral (antibody) immunodeficiency
 Multiple myeloma. This involves multiple malignant masses
of plasma cells scattered throughout the skeletal system. (See
pp. 910-912 of the course text)
2. Secondary cell mediated immunodeficiency
 There may be transient suppression of CMI with temporary
viral infections
 Acquired immune deficiency syndrome is an example of a
more permanent type of CMI immunodeficiency
3. Secondary phagocytic immunodeficiency
 This type of immunodeficiency can be drug induced. Large
amounts of steroids and/or other chemotherapeutic agents
can severely suppress the number of phagocytic cells.
4. Primary complement immunodeficiency
 A hereditary disease known as angio-edema is an example
of an immunodeficiency state affecting the complement
system. The disease causes local and painful edema in the
skin, lungs and gastrointestinal tract. The C2 kinin pathway
is involved causing uncontrolled increase in the permeability
of the vessels at the affected sites.
Hypersensitivity
A hypersensitivity reaction occurs when an immune response
contributes to tissue damage rather than recovery. The term is
synonymous with allergic reaction. There are four types of reaction;
only type 1 will be dealt with here.
Type I Immediate or Anaphylactic
This type of reaction is mediated by IgE. IgE and an antigen form an
antigen-antibody complex on the surface of a mast cell with the release
of large amounts of the vasoactive substance histamine. Histamine
causes smooth muscle constriction (except for smooth muscle in blood
vessels) an increase in permeability of blood vessels. This reaction is
immediate and progressive. A generalized reaction is life threatening.
Not only is histamine released from mast cells in the respiratory and
gastrointestinal tracts but it is also released into the bloodstream from
basophils. Basophils are white blood cells which act as circulating mast
cells. Anaphylactic shock will be dealt with in a later unit
Rankin, Reimer & Then. © 2000 revised edition. NURS 461 Pathophysiology, University of Calgary
Unit 3 Disturbances of the Immune System
Autoimmune Linked Disease
1. Systemic lupus erythematosus,
2. Hashimoto’s thyroiditis,
3. Rheumatoid arthritis
27
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Unit 3 Disturbances of the Immune System
References
Ader, R. (Ed.). (1981). Psychoneuroimmunology. New York:
Academic Press.
AIDS Information. (1989). Oncology information services, 5(3).
Leeds University Press: Author.
Blalock, J. E. (1984). The immune system as a sensory organ.
Journal of Immunology, 132(3), 1067-1070.
Centers for Disease Control. (1981). Kaposi’s sarcoma and
pneumocystis pneumonia among homosexual men: New York City and
California. Morbidity and Mortality Weekly Review, 30, 305-307.
Centers for Disease Control (1993). Revised classification system
for HIV infection and expanded surveillance case definition for AIDS
among adolescents and adults. Morbidity and Mortality Weekly
Review.41(No.RR-17).
Friendland, G. H., & Klein, R. S. (1988). Transmission of the
human immunodeficiency virus: An updated review. International
Nursing Review, 35(2), 44-54.
Gallo, R. C., & Montagnier, L. (1988). AIDS in 1988. Scientific
American, 259(4), 41-48.
Giaguinto, W. L., De Rossi, A., & Laverda, A. (1988). Natural
history of pediatric HIV infection (Abstract #7227). Fourth International
Conference on AIDS. Stockholm, Sweden.
Grady, C. (1988). HIV: Epidemiology, immunopathogenesis and
clinical consequences. Nursing Clinics of North America, 23(4), 683-696.
Heyward, W. L., & Curran, J. W. (1988). The epidemiology of
AIDS in the U.S. Scientific American, 259(4), 72-81.
Mann, J.M., Chin, J., Piot, P., & Quinn, T. (1988). The
international epidemiology of AIDS. Scientific American, 259(4), 82-89.
Petrie, K.J., Booth, R.J., Elder, H., & Cameron, L.D. (1999).
Psychological influences on the perception of immune function.
Psychological Medicine, 29, 391-397.
Plant, S. M., & Friedman, S. B. (1981). Psychosocial factors in
infectious disease. In R. Ader (Ed.), Psychoneuroimmunology, pp. 11-30.
Porth, C. M. (2005). Pathophysiology – Concepts of Altered
Health States (7th ed). Philadelphia: Lippincott
Rankin, Reimer & Then. © 2000 revised edition. NURS 461 Pathophysiology, University of Calgary
Unit 3 Disturbances of the Immune System
29
Reckling, J., & Neuberger, G. (1987). Understanding immune
system dysfunction. Nursing 87, 17(9), 34-41.
Redfield, R. R., & Burke, D. S. (1988). HIV infection: The clinical
picture. Scientific American, 259(4), 90-99.
Royal Society of Canada. (1988). AIDS: A perspective for
Canadians. Ottawa: Author.
Solomon, G. F. (1987). Psychoneuroimmunology: Interactions
between central nervous system and immune system. Journal of
Neuroscience Research, 18, 1-9.
Solomon, G. F., & Moos, R. H. (1964). Emotions, immunity and
disease: A speculative theoretical integration. Archives of General
Psychiatry, 11, 657-674.
Soloman, P. (1990). Projections of the Australian AIDS epidemic.
Royal Society of Medicine: The AIDS Letter, 21, 1-3.
Taussig, M. (1984). Processes in pathology (2nd ed.). Scarborough:
Blackwell Mosby Book Distributors.
Van De Graaff, K. M., & Fox, S. I. (1992). Concepts of human
anatomy and physiology (3rd ed.). Dubuque, IA: Wm. C. Brown
Publishers.
World Health Organization Web site (2000).
http://www.unaids.org/epidemic_update/report/index. Report on global
HIV/AIDS epidemic – June 2000.
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Unit 3 Disturbances of the Immune System
Glossary
Acronym List
Checklist of Requirements

Read Print Companion: Disturbances of the Immune System

Porth, C. M. (2005). Pathophysiology – Concepts of Altered
Health States (7th ed). Philadelphia: Lippincott. Chapter 19
Answers to Learning Activities
Learning Activity #1
1.
2.
3.
4.
5.
6.
7.
b
c
c
a
c
e
b
Rankin, Reimer & Then. © 2000 revised edition. NURS 461 Pathophysiology, University of Calgary