The document provides an overview of the immune system, including definitions of immunity, classifications of immunity as natural or innate versus acquired, and mechanisms of the immune response. It describes physical and chemical barriers, white blood cells, inflammation, humoral immunity, cellular immunity, complement system, and abnormal immune responses. It also discusses nursing assessment and management related to immune function and health education topics.

1. Body defense mechanism
& Immunity
Shrooti Shah
M.Sc. Nursing
Batch 2011
Page 1

2. Objectives
1. Define immunity
2. Classify immunity
3. Explain mechanisms of natural and acquired
immunity
4. Discuss the response to invasion by
microorganisms.
5. Describe abnormal immune response
6. Discuss nursing process related to immune
system
Page 2

3. Immunity
• The term immunity refers to the body’s specific
protective response to an invading foreign agent
or organism.
• The human body has the ability to resist almost
all types of organisms or toxins that tend to
damage the tissues and organs. The capability
is called immunity.
Page 3

4. Types of immunity
1. Natural (Innate) immunity
2. Acquired (adaptive) immunity
Page 4

5. Natural and acquired immunity
Natural immunity Acquired immunity
1. Is a nonspecific 1. Specific immunity
immunity present at birth develops after birth
2. responses to a foreign 2. Increases in intensity
invader are very similar with repeated exposure
from one encounter to to the invading agent.
the next.
Page 5

6. Natural (Innate immunity)
• The basis of natural defense mechanisms is the
ability to distinguish between friend and foe or
self and non-self.
• Such natural mechanisms include
1. Physical and chemical barriers
– Skin and mucous membrane
– Antimicrobial substance in body secretions
2. The action of WBCs
3. Inflammatory response.
Page 6

7. Physical and chemical barriers
Skin and mucous membrane
• When skin and mucous membrane are intact
and healthy they provide a physical barrier to
invading microbes.
• Sebum and sweat secreted on to the skin
surface contains antibacterial and antifungal
substances.
• Hairs in the nose acts as a coarse filter.
• One way flow of urine from the bladder during
Page 7
micturation

8. Antimicrobial substance in body
secretions
1. Hydrochloric acid in gastric juice
2. Lysosomes
3. Saliva
4. Immunoglobulin in nasal secretions and saliva
5. Interferons
Page 8

9. White blood cell action
• WBCs participate in both the natural and the
acquired immune responses.
• Granulocytes include neutrophils, eosinophils
and basophils.
• Nongranular leucocytes include monocytes or
macrophages and lymphocytes.
• Lymphocytes consisting of B cells and T cells,
play major role in humoral and cell mediated
immune responses. Page 9

10. Inflammatory response
• Major function of the natural (non specific or
innate) immune system.
• Chemical mediators assist this response by
minimizing blood loss, walling off the invading
organism, activating phagocytes and promoting
formation of fibrous scar tissue and regeneration
of injured tissue
Page 10

11. Dysfunction of the natural immune
system
• Immunodeficiency
• Persistent inflammatory response
• Autoimmune bodies
Page 11

12. Acquired immunity
• Usually develops as a result of prior exposure to
an antigen through immunization or by
contracting a disease.
• Weeks or months after exposure to the disease
or vaccine, the body produces an immune
response that is sufficient to defend against the
disease upon re-exposure to it.
Page 12

13. Active and passive immunity
1. Active immunity: Active immunity means that
the individual has responded to an antigen and
produced his own antibodies, lymphocytes are
activated and the memory cells formed provide
long lasting resistance.
2. Passive immunity: In passive immunity the
individual is given antibodies produced by
someone else
Page 13

14. Response to invasion
• When the body is invaded or attacked by
bacteria, viruses, or other pathogens, it has
three means of defending itself:
1. The phagocytic immune response
2. The humoral or antibody immune response
3. The cellular immune response
Page 14

15. Phagocyte immune response
• The first line of defense
• Involves the WBCs (granulocytes and
macrophages), which have the ability to
ingest foreign particles.
• Phagocytes also remove the body’s own
dying or dead cells.
Page 15

16. Humoral and cellular immune
response
• A second response, the humoral immune
response (sometimes called the antibody
response), begins with the B lymphocytes,
which can transform themselves into plasma
cells that manufacture antibodies.
• The third mechanism of defense, the cellular
immune response, also involves the T
lymphocytes, which can turn into special
cytotoxic (or Killer) T cells that can attack the
pathogens themselves.
Page 16

17. Humoral immune response
1. Before exposure to a specific antigen, the clones of B
lymphocytes remain dormant in the lymphoid tissue.
2. On entry of a foreign antigen, macrophages in the
lymphoid tissue phagocytize the antigen and then
present it to adjacent B lymphocytes.
3. In addition, the antigen is presented to T cells at the
same time, and activated helper T cells are formed.
4. Those B lymphocytes specific for the antigen
immediately enlarge and take on the appearance of
lymphoblasts.
Page 17

18. Humoral immune response cont…
5. Some of the lymphoblasts further differentiate
to form plasmablasts, which are precursor of
plasma cells.
6. The mature plasma cells then produces gamma
globulin antibodies.
7. Other B lymphocytes differentiate into B-
lymphocyte clones with a memory for the
antigen.
Page 18

19. Primary response and secondary
response
Primary response Secondary response
1. Response for forming 1. Response that occurs
antibodies that occur on after second exposure to
first exposure to a the same antigen.
specific antigen.
2. Appears 1 week after, 2. Begins rapidly after
with weak potency and exposure to the antigen
short life (often within hours) is far
more potent, and forms
antibodies for many
months rather than for
only a few weeks.
Page 19

20. Role of antibodies

21. Antibodies
• The antibodies can inactivate the invading agent in one
of the several ways, as follows:
1. Agglutination: in which the multiple large particles with
antigens on their surface.
2. Precipitation: in which the molecular complex of soluble
antigen and antibody becomes so large that it is
rendered insoluble and precipitates.
3. Neutralization: in which the antibodies cover the toxic
sites of the antigenic agent.
4. Lysis: in which some potent antibodies are occasionally
capable of directly attacking membranes of cellular
agents and thereby cause rupture of the agent.
Page 21

22. Types of immunoglobulin

23. IgG
IgG (75% of total immunoglobulin)
• Appears in serum and tissues (interstitial fluid)
• Assumes a major role in bloodborne and tissue
infections.
• Activates the complement system.
• Enhances phagocytosis
• Crosses the placenta Page 23

24. IgA
IgA (15% of total immunoglobulins)
• Appears in body fluids (blood, saliva, tears,
breast milk, and pulmonary, gastrointestinal,
prostatic and vaginal secretions).
• Protection against respiratory, gastrointestinal
and genitourinary infections.
• Prevents absorption of antigens from food.
• Passes to neonate in breast milk for protection.
Page 24

25. IgM
IgM (10% of total immunoglobulins)
• Appears mostly in intravascular serum
• Appears as the first immunoglobulin produced in
response to bacterial and viral infections.
• Activates the complement system.
Page 25

26. IgD
IgD (0.2% of immunoglobulins)
• Appears in small amounts in serum
• Possibly influences B-lymphocytes differentiation
, but role is unclear.
IgE
IgE (0.004% of immunoglobulins)
• Appears in serum
• Takes part in allergic and hypersensitivity of
reactions
• Combats parasitic infections.
Page 26

27. Cellular immune response
• These develop gradually over a period of 24 to 48
hours after the second encounter with an antigen.
• T lymphocytes are primarily responsible for cellular
immunity.
• Stem cells continuously migrate from the bone
marrow to the thymus gland, where they develop
into T cells.
• By spending time in the thymus, these cells are
programmed to become T cells rather than
Page 27
antibody producing B lymphocytes.

28. Cellular immune response cont…
• T cells attack foreign invaders directly. Cellular
reactions are initiated by the binding of an antigen
with an antigen receptor .
• The T cells then carry the antigenic message, or
blue print, to the lymph nodes, where the
production of other T cells is stimulated.
• Some T cells remain in the lymph nodes and retain
a memory for the antigen. Other T cells migrate
from the lymph nodes into the general circulatory
system and ultimately to the tissues.
Page 28

29. Types of T cells
1. Helper T cells:
• When activated, helper T cells secrete
cytokines that attract and activate B cells,
cytotoxic T cells, natural killer cells,
macrophages and other cells of the immune
system.
• Helper T cells produce different types of
cytokines and determine whether the immune
response will be the production of antibodies or
cell mediated immune response.
Page 29

30. 2. Cytotoxic T cells
• Cytotoxic T cells is a direct attack cell that is
capable of killing micro-organisms and, at times,
even some of the body’s own cells.
• For this reason these are called killer cells.
• Cytotoxic attack the antigen directly by altering
the cell membrane and causing cell lysis and
releasing cytolytic enzymes and cytokines.
Page 30

31. 3. Supressor T cells
• They are capable of suppressing the functions of
both cytotoxic and helper T cells.
• It is believed that these suppressor functions
serve the purpose of preventing the cytotoxic
cells from causing excessive immune reactions
that might be damaging to the body’s own
tissues.
Page 31

32. Complement system
• Circulatory plasma proteins which are made in
the liver and activated when an antibody couples
with its antigen, are known as complement.
• Complement has three major physiological
functions:
a. defending the body against bacterial infection
b. bridging natural and acquired immunity
c. disposing of immune complexes and the byproducts
associated with inflammation.
Page 32

33. Complement system
Complement mediated immune response are summarized
as:
1. Cytolysis: Lysis and destruction of cell membranes of
body cells or pathogens.
2. Isosonization: Targeting of the antigen so that it can be
easily engulfed and digested by the macrophages and
other phagocytic cells.
3. Chemotaxis: chemical attraction of neutrophils and
phagocytic cells to the antigen.
4. Anaphylaxis: activation of mast cells and basophils with
release of inflammatory mediators that produce smooth
muscle contraction and increased vascular permeability.
Page 33

34. Abnormal immune reactions
1. Antibody mediated
2. Cell-mediated
3. Mixed antibody
Page 34

35. Antibody mediated reactions
• These occur within minutes of exposure to an
allergen (antigen).
• The most common manifestations of this type of
allergic reaction include: food allergies,
childhood eczema, hay fever, extrinsic asthma.
• In these conditions the released chemicals act
locally, causing different effects that depend on
the site.
Page 35

36. Acute systemic anaphylaxis (anaphylactic
shock)
• It is caused by the entry of an allergen into the
blood e.g. snake venom, injectable penicillin.
• There are profound effects throughout the body,
including generalized vasodilatation, leading to
severe hypotension and contraction of smooth
muscle in the respiratory tract, causing acute
breathing difficulties.
Page 36

37. Other antibody mediated reactions:
• Reaction of antibodies with cells that have
antigens on their cytoplasmic membranes may
cause the cells to rupture.
• Abnormal reactions to antibody/antibody
complexes sometimes result in them adhering to
the endothelium of blood vessels causing
inflammation and local damage.
.
Page 37

38. Cell mediated reactions
The antigen include:
1. Intracellular microbes, e.g. those causing
tuberculosis, measles, mumps.
2. Some vaccines, e.g. against smallpox.
3. Some metals and compounds that combine with
protein in the skin and cause allergic contact
dermatitis.
Page 38

39. Mixed reactions
Autoimmune diseases:
• Tissue damage and signs of disease as the
body fails to recognize its own tissues.
Destruction of the body’s own cells may be
either humoral or cell-mediated.
– Thyroid- Hashimoto’s thyroiditis
– Stomach- Addisonian pernicious anemia
– Cortex of the adrenal gland- addison’s disease.
– Pancreas-type I diabetes mellitus
Organ transplantation and rejection Page 39

40. Nursing process
Nursing assessment
• An assessment of immune function begins with
a health history and physical examination
Health history
1. Age
2. Nutrition
3. Infection and immunization
4. Allergy
5. Medications and blood transfusion
6. Lifestyle and other factors
Physical examination Page 40

41. Nursing management
• Assisting with medical measures aimed at
improving immune status and treating infection,
improving the nutritional status, and maintaining
bowel and bladder function.
• Careful hand hygiene, encouraging the patient to
cough and perform deep-breathing exercises at
regular intervals, and protecting the integrity of
the skin and mucous membranes.
• Use strict aseptic technique when performing
invasive procedures
Page 41

42. Nursing management cont…
• Assisting the patient in managing stress and in
adopting a lifestyle that enhances immune
system function.
• The patient or parents (if the patient is a child)
must be informed about the potential risks and
benefits of the treatment regimen.
• A major role of the nurse is to assist the patient
and family to understand the treatment options
and to cope with the uncertainties of treatment
outcomes. Page 42

43. Health education
• About the signs and symptoms that indicate
infection.
• Whenever they experience a symptom that is not
typical for them, they should contact their health
care provider.
• About any prophylactic medication regimen,
including dosage, indications, times, actions, and
side effects.
• Avoid others with infections and crowds.
Page 43

44. Health education cont…
• The patient and family also need to learn about
other ways to prevent infection.
• Instructed to monitor for subtle changes in
physical status and must be informed of the
importance of seeking immediate health care if
changes occur.
• About the importance of continuing the
treatment regimen and assisted in incorporating
it into their lives.
Page 44

45. References
1. Wilson KJW, Waugh A. Ross and Wilson Anatomy and
physiology in Health and illness. Eigth edition.
NewYork; Churchill Livingstone:1998.
2. Smeltzer SC, Bare B. Textbook of Medical surgical
Nursing. 10th edition. Philadelphia; Lippincott Williams
and wilkins: 2004.
3. Guyton AC, Hall JE. Textbook of Medical Physiology.
Eleventh edition. Philadelphia; Saunder (Elsevier) :
2006.
Page 45