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1. THE IMMUNE SYSTEM and
IMMUNITY

2. Immune System
l a biochemical complex that protects the
body against pathogenic organisms and
other foreign bodies.
l The structure, cells and soluble
constituents that allow the host to
recognize and respond to foreign
stimulus.

3. Primary Role of The Immune
Syatem
l Surveillance and destruction of
substances that are foreign to the body.
- bacteria, viruses, parasites or fungi

4. Primary Function of the Immune
System
1. To protect the body against invasion by
so called non-self substance.
(any and all substances that are considered
“foreign”)
2. To differentiate between “self” and “non-
self” and to destroy that which is “non-
self”

5. Origin, Destination and Structure
of the Cells and Tissues

6. Bone Marrow
q constitutes almost 5% of the total body
weight and is responsible for the formation
of all blood cells in adult

7. Stem Cells
q all cells originates from undifferentiated
pluripotential hemopoietic stem cells, which
can be found first in the mammalian
embryo with in the liver then the spleen.
q are pluripotential CD34+

8. l Erythropoiesis
q occurs when a CFU-S cell gives rise to
burst-forming units-erythrocytes
l granulocytopoiesis
q the generation of three types of
granulocytes
l monocytes
q more pathogenic than neutrophils or
eosinophils

9. Dendritic Cells
q are bone marrow derived cells specialized
for presenting antigens to either CD4+ or
CD8+ t cells in order to initiate a primary
immune response.

10. Thymus
q is a primary lymphoid organ that is
required for the generation of
immunocompetent CD3+4+ & CD3+8+
cells necessary for an adaptive immune
response.

11. Lymph Nodes
q are encapsulated structures that are
strategically placed throughout the body to
receive and filter antigens & cells from
peripheral interstitial fluid and lymph.

12. Localization of Cells
1.Superficial cortex
q containing primary & secondary follicles
with germinal centers containing dark and
light zone
2. Deep cortex
q containing high endothelial post-capillary
venules
3. Medulla
q with medullary cortex

13. Spleen
l is an encapsulated organ
with lymphoid tissue called
white pulp(WP), which can
respond to blood-borne
antigens surrounded by the
red pulp(RP).
l Mucosal Associated
Lymphoid Tissue (MALT)

14. T Cells
l about half of the stem cells migrates to
the thymus gland where they
differentiate into T lymphocytes or T
cells
l small lymphocytes found in the blood
l about 70%-80% of the lymphocytes in
peripheral blood are T cells.

15. Two immunologic Functions of T
cells
1. Effector
q includes the cytolysis of virally infected
cells & tumor targets & the production of
lymphokines
2. Regulator
q includes the ability to amplify or suppress
other effector lymphocytes

16. Most of the T-cells express three
of the following CD Markers
l CD2
l CD3
l CD4
l CD8

17. Two Subpopulation of T cell in
the Circulation
1. Those with CD2, CD3, CD4 phenotype
2. Those withCD2 ,CD3, CD8 phenotype

18. includes:
1. Helper T cells (Th cells)
2. Suppressor T cells ( Ts cells)
3. Cytotoxic T cells (Tc cells )
4. Delayed hypersensitivity T cells (Td cells)

19. B cells
l Other lymphocytic stem cells
differentiate in the liver & intestinal
lymphoid areas into B lymphocytes or B
cells.
l About 10%-15% of the lymphocytes in
peripheral blood are B cells.
l Each is capable of producing hundreds
of specific antibodies per second

20. IMMUNITY
in positive sense:
q providing natural resistance, recovery, and
acquired resistance to infectious disease.
in negative sense:
q may result in rejection of a life-saving
transplant

21. Types of Immunity

22. Natural or Innate
q present at the time of birth or that
develops during maturation

23. - refers to anatomical, cellular, and humoral
defenses that function in the early stages
of host defense response to foreign
substances (antigens)
- cells that function in innate immunity does
not possess immunological memory.
- they are nonspecific because the cells do
not express receptors specific to one
particular antigen.

24. Acquired or Adaptive
q which is acquired as a result of prior
experience with a foreign substance

25. Further divided into:
humoral immunity (gut associated tissue GALT)
q is mediated by the antibody secreted by terminally
differentiated B cells, the plasma cells
q Type I, II, III hypersensitivity reactions
Cell mediated immunity (Thymus)
q involves T cells that recognize antigen in an MHC-
restricted fashion
(CD4 - T-helper cells, CD8 - T-suppressor cells)
q tissue graft rejection, delayed hypersensitivity
reaction, mononuclear inflammatory reaction

26. Characteristic of Natural
Immunity
1. Do not possess immunologic memory
2. Non specific
• operates as the first line of defense against
pathogens
includes the Physical barriers:
– Skin
– Mucous membrane
– Susceptibility & nonsusceptibility
– The provision of an unfavorable environment for the
infecting organism

27. Host defense in Innate Immunity
1. Cells
q antigen presenting cells
q basophils
q eosinophils mast cells natural killer cells
phagocytes
2. Humoral Factors
q complement proteins
q lactoferrin (present in tears, sebaceous & sweat glands)
q lysozymes

28. 3. Anatomical Barriers
q cilia
q mucus membrane
q skin
4. Resident Flora
q mainly nonpathogenic bacteria
q prevents colonization of new
microorganisms.
(intestine, vagina & nasopharynx)

29. Other factors that forms the
overall action of innate immunity
1. Inflammation
2. Complement
3. Phagocytosis

30. Adaptive immunity
1. Acquired adaptive immunity
q is highly specific, inducible, discriminating &
unforgetting.
- cell surface receptors are specific for a particular antigen.
- memory because lymphocytes that have been
activated in response to a particular antigen will
respond much faster in a subsequent exposure to
the same antigen.
q T lymphocyte dependent response.

31. TwoTypes of Adaptive immunity
1. Acquired active immunity
q by actual infection or inoculation that
causes the production of specific protective
antibodies
(vacines - hepatitis, tetanus)
2. Acquired passive immunity
q afford temporary protection against
invading antigen.
(RhIg given during birth, HBIg)

32. Characteristic of Adaptive
Immunity
1. With Memory
2. Specific

33. Host Defense in Adaptive
immunity
1. Cells
q B cells
q plasma cells
q T cells (cytotoxic & helper cells)
2. Humoral factors
q antibodies
q cytokines

34. Factors involved in the degree of
infection
l size of infecting dose
l route of administration
l type of infective agent

35. Nothing is predestined: The
obstacles of your past can
become the gateways that
lead to new beginnings.
Thank you and God
bless!!!