Chapt 0. Overview of Immunology 2021.ppt

Overview of immunology

1. Topics to be covered by myself
1.Introduction to Immunology
2. Cells of the Immune System
3. Organs of the Immune System
4. AIDS and other Acquired Immunodeficiencies
5. Transplantation and Reproduction Immunology
6. Cancer and Immune System

2. Introduction to Immunology
Kenneth Luryama Moi
Dept of Medical Microbiology &
Immunology

3. Teaching objectives
1.Be able to understand by definition what
immunology is all about
2.Recognize the significance of the immune
system
–What is the role/purpose?
–What are the mechanisms of protection?
3.Distinguish between the innate and adaptive
immune response (IR)
–What are the key features differentiating these two
arms of the immune system?

4. Is a branch of biomedical science that covers
the study of immune systems in humans. It
charts, measures, and contextualizes
the: physiological functioning of the immune
system in states of both health and diseases.
Human Immunology by definition
Immunis
Comes from Latin word “exempt”

5. Applications of Immunology
Used in various disciplines of medicine;
Organ transplantation
Oncology
Virology
Bacteriology
Parasitology
Psychiatry &
Dermatology

6. Organs, Tissues & Cells involved in
Immune System
• The important lymphoid organs of the immune system
are the thymus & bone marrow.
• Chief lymphatic tissues are the spleen, tonsils, lymph-
vessels, lymph nodes, adenoids, and liver.

7. •Most components of the immune system are
typically cellular in nature and not associated with any
specific organ; but rather are embedded or circulating
in various tissues located throughout the body.

8. 1.Classical Immunology
It studies the relationship between the body systems,
pathogens, and immunity.

The earliest written mention of immunity can be traced
back to the plague of Athens in 430 BC.
Thucydides noted that people who had recovered from a previous bout
of the disease could nurse the sick without contracting the illness a
second time.

Many other ancient societies have references to this
phenomenon, not until the 19th and 20th centuries before
the concept developed into scientific theory.

9. Sub-divisions of the Immune System
The immune system has been divided into:

 a more primitive innate immune system and

 an acquired or adaptive immune system
o humoral (or antibody) and 
o cell-mediated components

10. Overview of the immune system

11. The humoral (antibody) response is defined as the
interaction between antibodies and antigens.
Antibodies are specific proteins released from a certain
class of immune cells, B lymphocytes
Antigens are defined as anything that elicits the
generation of antibodies ("anti"body "gen"erators).

NB: Immunology rests on an understanding of the
properties of these two biological entities and the cellular
response to both
More definitions

12. Purpose:
1.Protection from pathogens
• Intracellular (viruses, some bacteria and
parasites)
• Extracellular (most bacteria, fungi, and parasites)
2.Eliminate modified or altered “self”
• Cancer or transformed cells
Methods of defense:
 Mechanical
 Humoral
Cellular

13. 2.Clinical Immunology
oAn illness is a broad concept while disease refers to a specific
condition that can be diagnosed by a healthcare provider.
oA disease is a pathological process that healthcare providers
are able to see, touch, and measure. Diseases have particular
signs and symptoms.
oSyndromes are groups of symptoms associated with a disease.
Knowing the syndrome can help diagnose the disease.
oA disorder is characterized by functional impairment and a
disruption to the body’s normal function and structure.
oA condition indicates your state of health. It is an abnormal
state that feels different from your normal state of wellbeing.
More terminologies

14. The study of diseases caused by:

i.Disorders of the immune system
•(failure, aberrant action, and malignant growth of
the cellular elements of the system)
e.g.
oImmunodeficiency,
oChronic granulomatous disease (CGD) and
oPrimary immune deficiency diseases (PIDDs)
Clinical Immunology (con’t)

15. ii.Autoimmunity
e.g.
•Systemic lupus erythematosus (SLE)
•Rheumatoid arthritis 
•Hashimoto’s disease and 
•Myasthenia gravis
Clinical Immunology (con’t)

16. Clinical Immunology (con’t)
iii.It also involves diseases of other systems, where
immune reactions play a part in the pathology
and clinical features
•Include various hypersensitivities (asthma and
other allergies) that respond inappropriately to
otherwise harmless compounds.
iv.Clinical immunologists also study ways to prevent
the immune system's attempts to
destroy allograft (transplant rejection)

17. 3.Developmental Immunology
The body’s capability to react to antigen
depends on;
 a person's age
 antigen type
 maternal factors and
 the area where the antigen is presented
Concerns with factors responsible for development
of immune cells and organs in an organisms body. 

18. i.In Neonates
Neonates are in a state of physiological
immunodeficiency, as their innate & adaptive
immunological responses being greatly suppressed.


Once born, a child’s immune system responds favorably
to protein antigens while not as well glycoproteins
& polysaccharides.
 Most infections are caused by low virulence organisms
e.g. Staph and Pseud.

19. oOpsonic activity and the ability to activate the
complement cascade is limited
oPhagocytic activity is greatly impaired
oMonocytes are slow with reduced ATP production, this
limits their phagocytic activity
oAPCs in newborns have a reduced capability to activate
T cells

oT cells proliferate poorly and produce very small amounts
amounts of cytokines - limits their capacity to activate
the humoral response and the phagocytic activity of
macrophage
oB cells develop early during gestation but not fully active

20. Maternal factors also play a role in the body’s immune
response.
•At birth, the immunoglobulin present is maternal IgG.
•Some IgA is provided by breast milk. The acquired Abs give
protection up to 18 months, but their response is usually
short-lived and of low affinity. 
Response of T-cells to vaccination differs in children
compared to adults, and vaccines that induce Th1 responses
in adults do not readily elicit these same responses in
neonates. 
Between 6-9 months after birth, a child’s immune system
begins to respond more strongly to glycoproteins,
and polysaccharides until they are at least one year old.

21. ii.In Adolescence
Both 17--oestradiol (an oestragen) & testosterone are
known to have an effect on the development and regulation
of the immune system, including an increased risk in
developing pubescent and post-pubescent autoimmunity. 
Cell surface receptors on B cells and macrophages may
detect sex hormones in the system.
17-β-oestradiol regulates the level of immunological
response, while testosterone seem to suppress the stress
response to infection. The sex hormones exhibit more control
of the immune system during puberty and post-puberty than
during the rest of a male's adult life.
Physical changes during puberty such as thymic
involution also affect immunological response.

22. 4.Immunotherapy
Is the use of immune system components to treat
a disease or disorder.
Immunotherapy is most commonly used in
 the treatment of cancers together
with chemotherapy and radiotherapy.
 Often used in the immunosuppressed (such
as HIV patients) & people suffering from other
immune deficiencies or autoimmune diseases. This
includes regulating factors such as IL-2, IL-10, GM-CSF
B, IFN-α.

23. 5.Diagnostic Immunology
The specificity of the bond between antibody and
antigen has made it an excellent tool in the detection
of substances in a variety of diagnostic techniques.
 Antibodies specific for a desired antigen can be
conjugated with an
 
isotopic (radio) 
or 
fluorescent
label 
or with a color-forming enzyme in order to detect
it.
Note: The similarity between some antigens can lead
to false positives and other errors in such tests by
antibodies cross-reacting with antigens that aren't
exact matches.

24. 6.Cancer Immunology
The study of the interaction of the immune
system with cancer cells can lead to diagnostic
tests and therapies with which to find and fight
cancer.

25. 7.Reproductive Immunology
This area of the immunology is devoted to the study of
immunological aspects of the reproductive process
including fetus acceptance.
The term has also been used by fertility clinics to
address fertility problems, recurrent miscarriages,
premature deliveries and dangerous complications such
as pre-eclampsia

26. 8.Theoretical Immunology
1."cellular" and "humoral" theories of immunity (19
th
& 20
th
C).
 According to the cellular theory of immunity, it was cells –
more precisely, phagocytes – that were responsible for immune
responses.
 In contrast, the humoral theory of immunity, stated that the
active immune agents were soluble components (molecules)
found in the organism’s “humors” rather than its cells
2.In the mid-1950s, the Clonal Selection Theory (CST), by Burnet
developed a theory of how an immune response is triggered
according to the self/nonself distinction: Later modified to
reflect new discoveries regarding histocompatibility or the
complex "two-signal" activation of T cells. 
3.More recently, several theoretical frameworks have been
suggested in immunology, including “autopoietic"
views, "cognitive immune" views, the “danger model" (or "danger
theory"), and the "discontinuity" theory. 

27. Cells of the immune system

28. Phases of the immune response
•Pathogen recognition
–Innate response is the same to repeated
exposures of the same pathogen
–Adaptive response matures over time; repeated
exposure leads to faster response
•Pathogen removal
–Early response: innate
–Later response: lymphocytes generate adaptive
immune response and memory

29. Comparison of innate and adaptive
immune response

30. Effects of the immune system
•Beneficial
–Protection from invader
–Elimination of altered self
•Detrimental
–Inflammation (local damage and discomfort)
–Damage to self (hypersensitivity or autoimmunity)

31. Balance
Disease = (bolus of infection x virulence)
immunity
infection immunity