The document provides an overview of immunology and defines key terms. It discusses the categories of the immune system as innate immunity and adaptive immunity. Innate immunity is non-specific and acts rapidly through physical and chemical barriers, as well as phagocytes. Adaptive immunity is specific and works more slowly through antibodies produced by B cells and cellular responses mediated by T cells. It also describes the basis of effector molecules and development of both the humoral and cell-mediated responses in adaptive immunity.

1. TOPIC 1 INTRODUCTION
TO IMMUNOLOGY
NS1122 BASIC SCIENCE 3:
IMMUNOLOGY
DIPLOMA IN NURSING
MDM SITI BAINUN BINTI
MOHD DALI

2. LEARNING OUTCOME
At the end of this lecture, students should be able to:
√ State the definition of immunology
√Define the important terms related to immunology
√Explain the categories of immune systems

3. 1. IMMUNOLOGY AND ITS
TERMINOLOGY

4. WHAT IS IMMUNOLOGY?
Immunology is the study of
physiology mechanisms that
humans and other animals use to
defend their bodies from invading
organisms.
Example of invading organisms: bacteria,
fungi, viruses, fungi, parasites, and toxins

5. In other words, immunology is the study
on how our body’s mechanism:
1.Protect against infectious disease
2.Distinguish self from non-self
component
3.Eliminate damages/malignant cells and
non-self component

6. 2. CLASSIFICATION OF
IMMUNE RESPONSE

7. 2.1 IMMUNE SYSTEM
Immune system is typically associated with
defending against foreign intruders, called
pathogen.
The immune system protects us from infection
through various lines of defense
If the immune system is not functioning as it
should, it can result in various diseases, such as
autoimmune, allergy, cancer and etc.

8. 2.2 CATEGORIES OF IMMUNE
SYSTEM
The immune system has been
divided into:
1.Innate immunity
2.Adaptive immunity /acquired
immunity

9. IMMUNE SYSTEM
INNATE SYSTEM
•Non specific
•Rapidly, broad specificity
External System: Physical
Barrier and chemical barrier
Internal System: phagocytes,
WBCs, Complement systems,
NK cells
ACQUIRED SYSTEM
Specific
Works slowly, antigen-
specific
Basis Of Effector Molecules
Humoral: mediated by B-
cells and produces
antibodies
Cell Mediated: mediated by
T-cells
Basis of Mode of
Development
Active: produce their own
antibodies
Passive: receives antibody
from external

10. 2.2.1 INNATE IMMUNITY

11. INNATE SYSTEM
•Non specific
•Rapidly, broad specificity
External System: Physical
Barrier and chemical
barrier
Internal System:
Phagocytes, WBCs,
Complement systems, NK
cells

12. 2.2.1 INNATE IMMUNITY
They are also referred as “non-specific
immunity”
Innate immunity is the body first line
of defense against pathogen uses
mostly physical and chemical barriers.
Works rapidly (within minutes) and
has broad specificity.

13. CLASSIFICATION OF INNATE
IMMUNITY
Can be further divided into two:
i. External Defense (first line defense): include
physical barriers (skin, mucus, nasal hair, cilia) and
chemical barriers (oil and sweat, stomach acid,
cerumen, lysosome in tears and tissue fluid, vaginal
bacteria producing lactic acid.)
ii. Internal defense(second line defense): phagocytes
(macrophages) and WBCs (neutrophils and
monocytes), inflammatory reactions, interferons,
complement system, fever, Natural Killer Cells (NK
cells)

14. INNATE IMMUNITY: MECHANISM OF
EXTERNAL DEFENSE
1. Physical barriers (skin and mucous membrane)
2. Chemical factors (antimicrobial substances)
3. Commensal flora

15. Intact skin is impenetrable to most of the bacteria. Its
low pH and presence of fatty acid makes the environment
inhospitable for bacteria other than commensals.
The continual shedding of the squamous epithelium also
reduces the bacterial load.
Mucus membranes- form less formidable barrier. The
mucus with entrapped bacteria is swept away by cilia of
the ciliated respiratory mucosa or the villi in the intestine.
Particles are swallowed and coughed out by cough
reflex.
1. PHYSICAL BARRIERS (SKIN AND
MUCOUS MEMBRANE)
INNATE IMMUNITY:
EXTERNAL DEFENSE

16. i). Skin has two Layers:
Epidermis: Thin outer layer of epithelial tissue. Contains
Langerhans cells, dead cells, and keratin (waterproof).
Dermis: Thick inner layer of connective tissue. Infections
are rare in intact skin. Exceptions:
i. Hookworms can penetrate intact skin
ii. Dermatophytes: “Skin loving” fungi
1. PHYSICAL BARRIERS (SKIN AND
MUCOUS MEMBRANE)
INNATE IMMUNITY:
EXTERNAL DEFENSE

17. Intact Skin is an Effective Barrier Against Most Pathogens
INNATE IMMUNITY:
EXTERNAL DEFENSE

18. 2. CHEMICAL FACTORS
(ANTIMICROBIAL SUBSTANCES)
The barrier defense of skin and mucus membrane are
reinforced by the presence of antibacterial substances.
Lysozyme, an enzyme present in most secretions degrade
bacterial peptidoglycan.
In acute phase of infection, pathogens ingested by
macrophages stimulate the synthesis and secretion of several
cytokines. Cytokines such as interleukin-1 and interleukin-6
travel through the blood and cause the liver to synthesize and
secrete acute phase proteins into the blood.
INNATE IMMUNITY:
EXTERNAL DEFENSE

19. 3. COMMENSAL FLORA
Prevents colonization by pathogens.
Alteration of normal resident flora may lead to invasion
by extraneous microbes causing serious disease, such as
staphylococcal and clostridial enterocolitis following
antibiotics.
Commensals protect the host by various mechanisms.
Competition for available food and tissue receptors.
Production of toxic substances such as fatty acids or
antagonistic substance such as bacteriocins.
Stimulation of antibodies (natural antibody) that may
cross-react with pathogens.
Keeping the immune system primed so that the
monocytes bear class II histocompatibility antigens
needed for immune response.
INNATE IMMUNITY:
EXTERNAL DEFENSE

20. INNATE IMMUNITY: MECHANISM OF
INTERNAL DEFENSE
1. Phagocytes (macrophages)
2. Inflammatory reactions
3. Interferons
4. Complement system
5. Natural Killer Cells (NK cells)

21. 1. PHAGOCYTOSIS
Most of the bacteria that enter into host are killed by phagocytic cells such
as Neutrophils and macrophages.
Steps in phagocytosis:
1. At first phagocyte approaches to the site of infection
2. Phagocyte extends pseudopodia around bacterial cell.
3. Pseudopodia gradually increase in size and finally fused so that bacteria is
engulfed in the form of phagosome or food vacuole.
4. The phagosome and lysosome come nearer to each other and fuse to
form phago-lysosome.
5. Inside phago-lysosome ingested bacteria is killed by hydrolytic and
digestive enzyme of lysosome.
6. Required materials released from digested bacteria are absorbed into
surrounding cytoplasm and undigested residues are excreted out by
exocytosis.
INNATE IMMUNITY:
INTERNAL DEFENSE

22. INNATE IMMUNITY:
INTERNAL DEFENSE

23. 2. INFLAMMATION
Inflammation is an important defense mechanism of
host to prevent infection. It is induced in response to
tissue damage caused by microorganism, toxins or by
mechanical means.
The inflammation may be acute; for eg. in response to
tissue damage or chromic; for eg. Arthritis, cancer etc.
Main aim of inflammation is to prevent spread of
injected microorganism or toxin from site of injection
and kill them on spot by phagocytosis.
INNATE IMMUNITY:
INTERNAL DEFENSE

24. Steps in inflammation response:
1. Damaged tissue releases histamine. Histamine
will stimulate an immediate inflammatory
response.
2. Histamine will:
1. cause the blood capillaries to expand for more
blood to flow to the infected area
2. Increase permeability of blood capillaries to
phagocytosis. The phagocytes and clotting factors
will accumulate in the infected area.
3. The blood clotting mechanism is triggered
4. The phagocytes carry out phagocytosis
INNATE IMMUNITY:
INTERNAL DEFENSE

25. INNATE IMMUNITY:
INTERNAL DEFENSE

26. CHARACTERISTICS OF
INFLAMMATION:
i. Redness
ii. Swelling
iii.Heat
iv.Pain
v. Loss of function
INNATE IMMUNITY:
INTERNAL DEFENSE

27. 3. INTERFERON (INF)
Interferons are set of glycoproteins which are released by the cells
that infected by virus in vivo and which reacts with uninfected cells so
as to make them resistant to infection to virus by blocking viral mRNA
transcription.
There are THREE (3) types of interferons:
INNATE IMMUNITY:
INTERNAL DEFENSE

28. 4. COMPLEMENT SYSTEM
A series of 11 proteins that are activated by antigen-
antibody complexes.
Activation of the complement increases phagocytosis and
destruction of the microbial organisms that enter the body
of an individual.
The system perform function in different ways:
1. Complement proteins ruptures the cell membranes of microbes
2. Stimulates mast cells to produce histamine
3. Strengthens the inflammatory reaction
4. Act as chemokines
5. Attract phagocytes to the infected area.
INNATE IMMUNITY:
INTERNAL DEFENSE

29. 5. NATURAL KILLER CELLS (NK
CELLS)
These are one of the type
of lymphocytes
The cells lyses the viral
infected body cells and
abnormal cells which could
form tumours.
INNATE IMMUNITY:
INTERNAL DEFENSE

30. 2.2.2 ACQUIRED IMMUNITY

31. 2.2.2 ACQUIRED IMMUNE SYSTEM
They are also referred as “specific immunity”
It is third line of defense
Adaptive immune system works slowly (starts in days) and
more complex that the innate
Adaptive immunity involves antigen-specific immune
response. Meaning that the immune system recognizes,
attacks, destroys, and remembers (memory) each pathogen
that enters the body. It does this by making specialized
cells and antibodies that render the pathogens harmless.
For each type of pathogen, the immune system produces
cells that are specific for that particular pathogen.

32. CLASSIFICATION OF ACQUIRED
IMMUNITY ACQUIRED SYSTEM
Specific
Works slowly, antigen-
specific
Basis Of Effector Molecules
Humoral: mediated by B-
cells and produces
antibodies
Cell Mediated: mediated by
T-cells
Basis of Mode of
Development
Active: produce their own
antibodies
Passive: receives antibody
from external

33. 2.2.2.1 BASIS OF EFFECTOR
MOLECULES

34. HUMORAL IMMUNITY
immunity that is mediated by antibodies (B cells).
promotes the development of normal operation
antibodies
Antibodies production:
1. Antibodies produced by B-lymphocytes and plasma
cells in lymphoid organs and bone marrow
2. derived from long-lived antibody-producing plasma
cells generated by previous antigen exposure and,
in secondary immune response, by the activation of
memory B cells.
HUMORAL IMMUNITY

35. CLASSES OF ANTIBODIES AND ITS
FUNCTION
CLASSES OF
ANTIBODIES
FUNCTIONS
Immunoglobulin
gamma (IgG)
The only antibody that can cross the placenta and confer immunity on
the fetus
Enhances phagocytosis, neutralizes toxins and viruses, protects fetus
and newborn.
Immunoglobulin
alpha (IgA)
Found in mucous secretions of the respiratory tract and the upper part
of the digestive tract and the vagina and colostrum.
Localized protection of mucosal surfaces. Provides immunity to infant
digestive tract.
Immunoglobulin mu
(IgM)
First antibodies produced during an infection. Effective against microbes
and agglutinating antigens. This is important in the initial activation of
B-cells, macrophages, and the complement system.
Immunoglobulin
epsilon (IgE)
Most importantly activates histamine secreting cells. Mediator in
allergic responses.
Also appears to play a role in parasitic infection. Possibly lysis of worms.
HUMORAL IMMUNITY

36. DEFENSIVE MECHANISM BY
ANTIBODIES
Antibodies do not destroy antigens, they inactivate and tag
antigens for destruction.
1. Neutralization
2. Opsonization
3. Agglutination
4. Precipitation
5. Antibody-dependant cellular cytotoxic
6. Complement fixation
HUMORAL IMMUNITY

37. NEUTRALIZATION
Antibodies bind to and blocks
specific sites on viruses and
bacteria, thus preventing
these antigens from binding
to receptors on tissue cells
Later destroyed by
phagocytes
HUMORAL IMMUNITY

38. AGGLUTINATION
Antibodies bind the same
determinant on more than one
antigen
Makes antigen-antibody
complexes that are crosslinked
into large lattices (agglutination)
IgMs are good at this with
mismatched blood.
HUMORAL IMMUNITY

39. PRECIPITATION
Type of antigen-antibody
reaction, in which the
antigen occurs in a soluble
form.
When a soluble antigen
reacts with its specific
antibody, antigen-antibody
complex forms insoluble
precipitate.
HUMORAL IMMUNITY

40. COMPLEMENT FIXATION
Main mechanism used against cellular antigens
Antibodies bound to cells, change shape and expose
complement binding site
This triggers complement fixation on the antigenic cell
surface resulting in cell lysis.
HUMORAL IMMUNITY

41. OPSONIZATION
Antibodies acts as opsonin to tag foreign pathogen for
elimination by phagocytes.
Opsonin are used to overcome the repellent force
(negatively charged cell walls of pathogen and phagocytes)
between the negative cell walls and promote uptake of the
pathogen by the macrophage.
HUMORAL IMMUNITY

42. ANTIBODY-DEPENDANT
CELLULAR CYTOTOXIC
NK cells and other leukocytes bind to antibody coated
cells by Fc receptors and destroy these cells.
Eosinophils mediate a special type of ADCC directed
against some helminthic parasite.
Helminths are too large to be engulfed by phagocytes,
and their integument is relatively resistant to the
microbicidal products of neutrophils and
macrophages, but they can be killed by a basic protein
(histamine) present in the granules of eosinophils.
IgE coats the helminths, and eosinophils can then bind
to the IgE.
HUMORAL IMMUNITY

43. HUMORAL IMMUNITY

44. CELL MEDIATED IMMUNITY
CI composed of T-lymphocytes
Immune response in which body develops large
number of lymphocytes that are specifically activated
against foreign agent.
These activated lymphocytes have the ability to
attach to a foreign agent and destroy it.
Acts in the case of intracellular pathogens,
antibodies are ineffective because of their
CELL MEDIATED IMMUNITY

45. CELL MEDIATED IMMUNITY

46. TYPES OF EFFECTOR T CELLS
1. Regulatory T cells
a) T-helper cells:
 Interacts only with antigen-MHC II complex
 Potentiate both engulfment and killing by phagocytosis
 promote growth and differentiation of cells at the immune
response site.
 Stimulate B cells to produce antibodies.
b) T-regulatory (suppressor cells)
 suppress the activity of B cells and other T cells.
 inhibit antibody production by B cells,
 suppress the functions of the killer T cells and helper T cells.
CELL MEDIATED IMMUNITY

47. TYPES OF EFFECTOR T CELLS
2. Cytotoxic (killer) T cells: CD8+
Interacts with antigen-MHC-I molecule
Actions mediated by cytokines
activation of cytotoxic T cells lead to the
destruction of virus infected cells, tumor cells
or foreign cells.
CELL MEDIATED IMMUNITY

48. 2.2.2.2 BASIS OF MODE OF
DEVELOPMENT

50. BASIS OF MODE OF DEVELOPMENT
1. ACTIVE IMMUNITY: lymphocytes produce their
own antibodies as a response to stimulation by
the antigen.
i. Artificial active immunity: provided by vaccination
ii. Natural active immunity: provided by natural infection

51. BASIS OF MODE OF DEVELOPMENT
2. PASSIVE IMMUNITY: the body receives antibodies
from an external sources
i. Natural passive immunity: IgG antibody produced in
mother cross placenta and protects fetus up to 6mo
age. And transfer of maternal antibodies through milk
ii. Artificial passive immunity: preformed antibody are
injected into host for immunity. Eg: anti-venom,
Rabies vaccine

52. Broad range Highly specific
Humoral
Cellular

53. CHARACTERISTICS/ DIFFERENCES
OF INNATE AND ADAPTIVE
IMMUNITY
INNATE IMMUNITY ADAPTIVE IMMUNITY
Antigen independent Antigen dependent
No time lag A lag period
Not antigen specific Antigen specific
No immunologic memory Development of memory
Cells involved:
- Neutrophils (PMN)
- Macrophages
- Natural killer (NK) cells
Cells involved :
- T lymphocytes
- B lymphocytes
- Dendritic cells
- Eosinophils
- Basophils/mast cells

55. CHRONOLOGY OF THE IMMUNE
RESPONSE Bactericidal
molecules
Phagocytes,
Soluble
mediators
Antigen presentation, B and T cell
maturation

56. THANK YOU!