The Immune System

1. The Incredible Immune System
Or....

2. Why you're
not dead.

4. Who are these guys...
and why are they trying to
hurt (not kill) us?

5. PATHOGENS
∙Bacteria
∙Protists
∙Fungi
∙Parasites
∙Viruses

6. Bacteria

9. Warmth
Moisture
Nutrition

10. Protists

12. Warmth
Moisture
Nutrition

13. Fungi

16. Warmth
Moisture
Nutrition

17. Parasitic worms
and arthropods

18. Tapeworm

20. Ascaris

21. Filarial worm

25. Warmth
Moisture
Nutrition

26. Viruses

29. SPREAD OF PATHOGENS
∙food and water borne
∙air-borne...droplet infection (sneeze/cough)
∙contact infection
∙wound infection
∙arthropod carriers (insects and relatives)

30. HISTORICALLY INCREASED BY:
Global trade
Better transportation
Urbanization
Factory work
Public schools

31. GREATLY REDUCED BY:
Shoes
Pasteurization
Window screens
Air conditioning
Clean water!!!
Better hygiene, nutrition
Non-contaminated food
Antitoxins & vaccines

32. SELF VS. NON-SELF
∙organisms are biochemically unique
∙There are proteins on surface of every
cell...harmless to self; provoke a reaction within
another body
∙different in each individual
∙antigen = substance capable of stimulating a
response

34. FACTORS AFFECTING IMMUNITY
∙age
∙genetics
∙hormonal effects
∙physiological state
∙portal of entry
∙virulence of antigen
∙stress

36. ∙NON-SPECIFIC (first line)
∙skin
∙respiratory system
∙ears
∙eyes
∙mouth
∙stomach
∙urogenital tract
∙Interferons

37. second line of defense
∙local inflammatory response
∙mast cells release histamines
∙cause pain, heat, redness, swelling
∙cause constriction of some smooth muscles
(bronchioles)
∙blood vessels dilate...increase flow to area
∙cause permeability of capillaries to increase
∙serotonin
∙its action resembles histamine, but it causes
vasoconstriction of larger blood vessels
∙cytokines can also be produced if a virus is present
∙cytokines inhibit production of viruses

39. ∙general inflammatory response
(fever)
∙macrophages release interleukine
∙reset body’s thermostat in
hypothalamus
∙may be a way to slow down until
immune system can catch up

40. ∙phagocytosis
∙increased blood flow brings large
numbers of neutrophils and monocytes
∙NK (natural killer) cells
∙kill virally infected cells
∙may attack tumor and other
cancerous cells

42. 3rd Line of Defense: SPECIFIC - Takes several days to
activate
∙cells of this system must be able to distinguish between
self and non-self
∙proteins on cell surface membranes act as recognition
devices, called antigens
∙immune system is tolerant to the body’s own antigens
and does not attract them
∙There are two types of responses: cell mediated and
antibody mediated

44. Cell-Mediated Immunity (T-cells)
∙Macrophages engulf pathogens and bring them to lymphocytes
∙their information is “presented” to helper T-cells
∙Helper T-cells
∙Killer T-cells
∙Memory cells
∙Suppressor cells

46. Helper T-cells
∙make other lymphocytes competent
∙can stimulate B-cells to become plasma cells to make
antibodies
∙stimulate the production of other T and B cells
∙produce lymphokines which stimulate macrophages to
engulf more invading cells
∙can produce interleukines
∙enhance inflammation
∙stimulate killer T-cells

47. Killer T-cells
∙combine with antigens
∙attack cancer cells
∙cannot attack viruses directly, but can destroy cells
containing viruses
∙Once a virus enters a cell, it is safe from
antibodies.
∙Only T-cells destroying the cell can destroy the
virus
∙Cells containing viruses have viral antigens on
their surface...they can be recognized
∙release lymphokines

48. Memory cells
∙live for years in the lymphatic system
∙Memory T & B cells circulate in the lymph, ready to react with
their antigen
∙Antigens entering the body are carried by macrophages to a
lymphatic organ (spleen, tonsils, lymph nodes) where there is
a high conc. of T cells
∙Sometimes, swelling in nodes indicates an infection
∙At a second exposure, the response proceeds more rapidly
∙Pathogens are usually destroyed before they can cause any
symptoms
∙prevent you from getting the same disease twice

49. ∙Suppressor cells
∙reproduce slowly (1 week)
∙inhibit other cells
∙help prevent immune system
from
over-reacting to a stimulus

50. ∙Antibody-mediated immunity. (B-
lymphocytes)
∙After a macrophage has ingested a
pathogen, helper T-cells are activated as
before
∙The helper T-cells trigger specific B-
cells to proliferate and differentiate into
plasma cells

51. ∙B-cells
∙divide through mitosis and differentiate into
plasma cells
∙Plasma cells produce antibodies
∙Plasma cells do not leave the lymph nodes
∙The antibodies they produce travel to the
infected area

53. ∙an antibody is a globular protein that reacts to a
specific antigen
∙antibodies work to destroy antigens several
ways
∙agglutination
∙some produce antitoxins
∙lysis
∙some coat the pathogen
∙some stimulate phagocytosis
∙some stimulate the compliment system
∙Some B-cells produce memory cells

57. ∙AIDS = deficiency of t-lymphocytes
∙HIV attacks helper T-cells
∙results in abnormally high ratio of
suppressor T-cells to helper T-cells
∙suppressors inhibit secretions of killer
T-cells
∙and inhibit development of B-cells into
plasma cells

58. Types of Immunities
∙Active: antibody-antigen or T-cells react to antigen
∙natural: natural exposure to pathogen
∙artificial
∙exposure to dead or weakened pathogen (oral,
injection)
∙Passive: person is given antibodies
∙natural: person is given antibodies across
placenta/colostrum from mother
∙artificial: injection of antibodies produced in another
animal

61. Hypersensitivity
∙allergies: mild antigens induce a response which
non-allergic people don’t respond to
∙When exposed to allergen, Helper T-cells
stimulate B-cells to produce an antibody called
IgE (reagin)
∙IgE attaches to IgE receptors on mast cells
(large connective tissue cells) and basophils
∙Upon second exposure to allergen, it attaches to
IgE and causes mast cells to release large
amounts of histamines, causing inflammation,
edema, large amount of mucus secretion, etc.

63. Graft or transplant rejection
∙t-cell suppressors, like cyclosporin, are
used to reduce rejection of transplanted
organs
∙immunologically privileged sites
∙Sites where foreign tissue will not be
rejected
∙cornea, uterus