1. Immunity and Disease
The Lymphatic System

2. Body Defense Mechanisms
 The body’s defense system
 Three lines of defense
 Distinguishing self from nonself
 Antibody-mediated responses and
cell-mediated responses
 Steps of the adaptive immune response
 Active and passive immunity
 Monoclonal antibodies
 Problems of the immune system

3. The Body’s Defense System
 Targets of the body’s defense mechanisms
• Pathogens
• Disease-causing bacteria, viruses, protozoans,
fungi, parasitic worms, prions
• Cancer cells
• Once normal body cells whose genetic changes
cause unregulated cell division

4. Overview of Body Defenses
 Every day we encounter a vast number of health
threats
 Body defenses include physical barriers and two
interacting sets of cells and proteins

5. Three Lines of Defense Protect the Body
 Physical barrier to invasion
• Intact skin
• Linings of body cavities and tubes
 Innate immune system
• General, immediate response to antigens
• Does not target specific intruders
 Adaptive immune system

7. We Are Born with Some General Defenses
and Acquire Other, Specific Ones (1)
 Pathogens
• Viruses
• Bacteria
• Fungi
• Protozoa
• Parasitic worms
 Antigens
• Proteins
• Lipids
• Oligosaccharides

8. We Are Born with Some General Defenses
and Acquire Other, Specific Ones (2)
 Immunity
• Innate immunity
• Preset responses
• Immediate response
• Carried out by some white blood cells and
plasma proteins
• Adaptive immunity
• Slower response
• Carried out by lymphocytes and proteins
• Every adaptive response leaves behind cells that
“remember” a pathogen  basis of immunizations

9. White Blood Cells
The defenders
Produced by stem cells in bone marrow

10. Phagocytes
 Type of WBC
 Releases several types of cytokines
• “Cell movers” that promote and regulate immunity
• Interleukines
• Interferons

11. White Blood Cells & Their Chemicals Are
the Defenders in Immune Responses (1)
 Phagocytic white blood cells release chemical
signals and aid the immune system
• Cytokines
• Interleukins
• Interferons
• Tumor necrosis factor
• White blood cell enzymes
 Another chemical weapon
• Complement system (proteins)
• ~30 proteins
• Act as antimicrobials- flag microbes for destruction!

12. White Blood Cells & Their Chemicals Are
the Defenders in Immune Responses (2)
 Types of white blood cells:
 Neutrophils (2/3rds of our WBC’s)
 Basophils (release histamines)
 Mast cells (release histamines)
 Macrophages (engulf cells)
 Eosinophils (target worms, fungi, etc)
 Dendritic cells (alert immune system when antigen is in tissue
fluid in skin and body linings
 B and T Lymphocytes
• B cells and T cells: only cells with specific receptors
 Natural killer cells (NK cells- destroy cancer cells & cells
infected by viruses

13. The Lymphatic System
 Lymphatic system
• Picks up fluid lost from the capillaries and returns
it to the blood
• Defense
• Consists of: drainage vessels, lymphoid organs,
and lymph tissues
 Lymphoid organs
• Spleen
• Lymph nodes
• Others
 Lymph
 Fluid identical to interstitial fluid

14. Lymphatic System
 Elephantiasis
• A condition in which
parasites block
lymphatic vessels,
preventing the return
of fluid to blood
• Results in massive
swelling, darkening,
and thickening of the
skin in the affected
area

15. Lymphatic System
 Components of the lymphatic system
• Lymph
• Fluid identical to interstitial fluid
• Lymphatic vessels
• Vessels through which lymph flows
• Have one-way valves to prevent backflow
• Lymphoid tissues and organs

16. Tonsils
Defense against bacteria and other foreign agents
Right Lymphatic Duct
Drains right upper portion of the body
Thymus Gland
Site where certain white blood cells acquire means
to chemically recognize specific foreign invaders
Thoracic Duct
Drains most of the body
Spleen
Major site of antibody production; disposal site for
old red blood cells and foreign debris; site of red
blood cell formation in the embryo
Some Lymph Vessels
Return excess interstitial fluid and reclaimable
solutes to the blood
Some Lymph Nodes
Filter bacteria and many other agents of disease
from lymph
Bone Marrow
Marrow in some bones is production site for
infection-fighting blood cells (as well as red blood Stepped Art
cells and platelets) Fig. 9-2, p. 158

18. The Lymph Vascular System Functions
in Drainage, Delivery, and Disposal
 Lymph capillaries at the start of the drainage
network
• Collect water & solutes
 Merge into larger vessels containing smooth
muscles and valves
 Transport material to ducts of CV system

19. Lymph Capillaries Collect Fluid and
Direct It through Lymph Nodes

20. Lymph
 Lymph fluid returns to blood via large lymph
vessels that drain into veins in the lower neck

21. Lymphoid Organs and Lymphatic Tissues
Are Specialized for Body Defense
 Lymph nodes
• Lymphocytes and macrophages clear the lymph
of bacteria and other foreign substances
 Spleen
• largest lymphatic organ
• Filters blood
• Major site of antibody production
• Storage reservoir of red blood cells and
macrophages
 Thymus
• Site of T cell multiplication and specialization

22. Take Home
• What are the functions of the
lymphatic system?

23. Surface Barriers
Pathogens usually cannot get
past the skin or the linings of
other body surfaces such as
the digestive tract

24. Surface Barriers (1)
 Bacteria are normal inhabitants of the body
• Roles of bacteria
• On the skin
• In the mucosal lining of the digestive tract
• In the vaginal mucosa, e.g., Lactobacillus
 Effect of antibiotics on normal microbial
inhabitants, e.g., Lactobacillus
 Athlete’s foot

25. Vaginal Yeast Infection
http://yeastinfectionnomore.atarh.com/

26. Surface Barriers (2)
 Inner walls of the respiratory airways
• Sticky mucus
• Cilia
• Lysozyme
• Enzyme that fights bacteria
 More protection found in:
• Tears
• Saliva
• Gastric fluid
• Urine has low pH and flushing action
• Mild diarrhea

28. Innate Immunity
 Phagocytosis,
 …inflammation,
 …and fever…
 …are the body’s “off-the-shelf” mechanisms that
act at once to counter threats in general and
prevent infection

29. The Mighty Macrophage!

30. Innate Immunity (1)
 Once a pathogen enters the body:
 Macrophages arrive 1st (usually)
• Release cytokines if they detect antigen
• Cytokines are chemical signals that attract
dendritic cells, neutrophils, and more
macrophages
 Complement molecules activated
• Attract phagocytes (such as macrophages &
neutrophils)
• Bind to the pathogen
• May form membrane attack complexes
• Trigger inflammation

31. Inflammatory Response
 Inflammatory response
• Destroys invaders and helps repair and restore
damaged tissue
• Four signs
• Redness
• Heat
• Swelling
• Pain

32. Inflammatory Response
 Redness
• Mast cells release histamine, which causes blood
vessels to dilate
• Blood flow to the area increases, delivering
defensive cells and removing dead cells
and toxins

33. Inflammatory Response
 Heat
• Temperature rises as a result of increased blood
flow
• Speeds healing and activities of
defensive cells

34. Inflammatory Response
 Fever
• An abnormally high body temperature
• Caused by pyrogens
• Chemicals that reset the brain’s thermostat to a
higher temperature
• A mild or moderate fever helps fight bacterial
infection
• A very high fever (over 105°F or 40.6°C) is
dangerous

35. Inflammatory Response
 Swelling
• Histamine causes capillaries to become leaky
and fluid seeps into tissues
• Fluid brings clotting factors, oxygen,
and nutrients

36. Inflammatory Response
 Pain
• Can be caused by
• Excess fluid
• Bacterial toxins
• Prostaglandins

37. Acute sudden inflammation
 Activated complement and cytokines trigger this
fast, general response to tissue invasion
 Symptoms are redness, swelling, warmth, and
pain, all caused by this series of internal events 

38. Acute Inflammation Is a General
Response to Tissue Damage
Histamines ↑

39. Innate Immunity (2)
 Symptoms of inflammation include redness, swelling,
warmth, and pain
 Internal events of inflammation
• Mast cells release histamine
• Arteriole vasodilation
• Fluid and plasma leak out of capillaries leading to
edema (swelling)
• Bacteria attacked
• Clotting factors- wall off inflamed area
• Fever- develops when cytokines stimulate brain to
release prostaglandins
• Prostaglandins are signaling molecules that raise set point on
hypothalamic thermostat

40. Adaptive Immunity

41. Overview of Adaptive Defenses
 When physical barriers and inflammation don’t
prevent an invasion, the adaptive immune
system is mobilized

42. Adaptive Immunity Has Three Key
Features
 Adaptive immunity mobilizes B and T cells
1. Specificity- receptors for 1 kind of antigen form
2. Diversity- collectively, these cells may have
receptors for ~a billion different specific threats
3. Memory- some of the B and T cells are held in
reserve for future battles
 Effector cells
• Respond immediately to destroy pathogen
 Memory cells
• Set aside for a second or third encounter

43. Distinguishing Self from Nonself
 T cells and B cells
• B cells and T cells that respond to a particular
antigen divide repeatedly, forming two cell lines
• Effector cells
• Short-lived cells that attack the invader
• Memory cells
• Long-lived cells that remember the invader and
mount a quick response when it is next
encountered

44. Activated Lymphocytes Produce Effector
Cells and Memory Cells

45. Antibody-Mediated Responses
and
Cell-Mediated Responses

46. B Cells and T Cells Attack Invaders in
Different Ways
 B cells
• Produced in bone marrow, sent to lymphatic
system
• Produce antibodies; antibody-mediated
immunity- instead of direct engagement, produce protein
antibodies
 T cells
• Produced in bone marrow and go to the thymus
gland for development
• Cytotoxic T cells; cell-mediated immunity-
involves direct engagement
• Helper T cells- have both types of responses

48. Steps of the Adaptive Immune Response
1. Threat
• Foreign organism or molecule (an antigen) enters
the body
2. Detection
• Macrophage detects foreign organism or
molecule and engulfs it

49. Steps of the Adaptive Immune Response
3. Alert
• Macrophages present antigens to helper
T cells
• Macrophages are antigen-presenting cells
• Helper T cells are the main switch for the adaptive
immune response

51. Steps of the Adaptive Immune Response
4. Alarm
• Helper T cells activate appropriate B cells and T
cells to destroy the specific antigen
• When activated, these cells divide to form clones
of cells designed to eliminate the specific antigen
from the body

52. Steps of the Adaptive Immune Response
5. Building specific defenses
• B cells form plasma cells that secrete antibodies
into the bloodstream that bind to antigens
• T cells form cytotoxic T cells that attack

53. Steps of the Adaptive Immune Response
6. Defense: The cell-mediated response
• An effector cytotoxic T cell releases perforins,
which cause holes to form in cells with the
particular antigen

54. Steps of the Adaptive Immune Response
7. Continued surveillance
 Immunological memory allows for a more rapid
response on subsequent exposure to the antigen
 Primary response
 Occurs during body’s first encounter with a
particular antigen
 Antibody concentration rises slowly
 Secondary response
 Occurs during subsequent encounter with that
antigen
 Strong and swift due to the large number of
memory cells programmed to respond to that
particular antigen

57. B and T Cells

58. B & T Cells
 When mature, most move into lymph nodes, the
spleen, and other lymphoid tissue
 Remember- two different responses occur:
1) Antibody- mediated
2) Cell-mediated

59. How Do B & T Cells Learn?
 They study hard!
• Study groups
• Biojeopardy learning games
 Involves MHC markers
• Major histocompatability complex genes

60. MHC Markers Label Body Cells as Self
 MHC markers
• Major Histocompatibility Complex genes code for
these proteins
• Some of these proteins stick out of cell
membranes
• T cells have receptors that recognize them

62. Antibody-Mediated Immunity: Defending
against Threats Outside Cells
 Different kinds of antibodies have roles in body
defenses
 5 classes of antibodies

63. Antibodies Develop While B Cells Are in
Bone Marrow
 B cell in bone marrow develops antibodies
 Binding of antigens
• Copies of antibodies made by B cell, migrate to and
stick out of plasma membrane like ‘bristles’

64. Antibodies Can Bind to Antigens
antigen on bacterial
binding site for antigen binding site for antigen cell (not to scale)
binding site on one
kind of antibody
molecule for a
specific antigen
Typical Y-shape of simple antibody
Stepped Art
Fig. 9-12, p. 164

65. There Are Five Classes of Antibodies,
Each with a Particular Function
 Immunoglobulins (Igs)
• Proteins produced by B cells; various shapes
• Result from gene shuffling while B cell matures
during immune response
• Antigen-binding sites; other sites with special
roles
 Types of Igs (pg165)
• IgM
• IgD
• IgG
• IgA
• IgE

66. Cell-Mediated Responses: Defending
against Threats Inside Cells
 Responses by antibodies can’t reach threats
inside cells
 Accordingly, when cells become infected or
altered in harmful ways, other “warrior” cells
must come to the defense

67. Cell-Mediated Responses
 Starts when an antigen presenting cell (APC) presents
an antigen to a T cell
 Role of:
• Helper T cells and cytotoxic T cells  specific response
• NK cells and macrophages  more general response
 Target: viruses, bacteria, some protozoa and some
fungi, and cancerous cells
 Apoptosis

68. Protozoans
Giardiasis is an infection of the small
intestine caused by a microscopic
organism (protozoa), Giardia lamblia.
Abdominal pain, Diarrhea, Gas or bloating,
Headache, Loss of appetite, Low-grade
fever, Nausea, Swollen or distended
abdomen, Vomiting

69. T Cells Are the Warriors in Cell-Mediated
Immune Responses

70. T cell (orange) killing a cancer cell
(magenta).

72. Helper T Cells
 Their cytokines stimulate NK cells
 NK cells don’t need an antigen
 They simply attack any body cell that has too
few or altered MHC markers, or that antibodies
have tagged for destruction
 They also kill cells flagged with chemical “stress
markers” that develop when a cell is infected or
becomes cancerous

73. A Cytotoxic T Cell Touch-Killing a
Tumor Cell
Release chemicals that kill
on contact.
Also release chemicals that
cause genetically
programmed cell death-
apoptosis.

74. Cytotoxic T Cells Cause the Body to
Reject Transplanted Tissue
 MHC markers on donor cells recognized as
antigens by recipient cells
 Best donors have similar genetic makeup and
compatible blood type with recipient
 Recipient takes immuno-suppressing drugs and
often antibiotics to control infections
 Transplanted tissues of the eye and testicles do
not provoke an immune response

75. Immunological Memory
 The memory cells produced during an adaptive
immune response can provide many years of
immunity to a pathogen

76. Immunological Memory
 Memory cells form during primary (first) immune
response
• Circulate for years, even decades
• Patrolling battalions
 Even more memory T and plasma cells form
during a second adaptive response
 Memory cells determined by the type of antigen
exposure

77. Memory Cells Allow the Body to Mount a
Faster, Stronger Immune Response

78. Applications of Immunology
 Modern science has developed powerful
weapons that can enhance the immune system’s
functioning or harness it in new ways to treat
disease
 Vaccine  primary immune response to antigen
 Booster  secondary immune response; more
effector & memory cells form that can provide
longer lasting protection

79. Immunization Gives “Borrowed”
Immunity
 Immunization
• Vaccine: first injection + “booster shot”
• Killed or extremely weakened pathogens
• Inactive forms of natural toxins
• Transgenic viruses
 Passive immunization
• Injections of purified antibodies
• Does not confer memory cells though
 Adverse effects of vaccines

80. Passive Immunity to Infectious Disease
1955
 http://www.youtube.com/watch?v=9Bm2fnCTaMg

81. WHO: Prevent. Protect. Immunize.
 http://www.youtube.com/watch?v=sGKrs1ED_rw

82. Disorders of the Immune System
 In allergies, harmless substances provoke an
immune attack

83. In Allergies, Harmless Substances
Provoke an Immune Attack (1)
 Common allergens
• Pollen
• Variety of foods and drugs
• Dust mites
• Fungal spores
• Insect venom
• Ingredients in cosmetics
 Allergy
• Response and severity

84. The Basic Steps Leading to an Allergic
Response
Role of IgE antibodies

85. In Allergies, Harmless Substances
Provoke an Immune Attack (2)
 Symptoms of allergies vary
• Inflammation of mucus membranes
• Constriction of airways
• Stuffed sinuses, drippy nose, and sneezing in
hay fever
• Vomiting
• Diarrhea
 Anaphylactic shock
• Whole-body allergic response
• Can be fatal

86. Autoimmune Disorders Attack “Self”
 Autoimmune disorders
• Rheumatoid arthritis
• Type I diabetes
• Insulin secreting cells of pancreas attacked
• Systemic lupus erythematosus
 Immune systems “weapons” unleashed upon
own body
 More common in women- is receptor for
estrogen involved??

87. Immune Responses Can Be Deficient
 Immunodeficiency
• Weakened or missing immune system
 Severe combined immune deficiency (SCID)
• Short supply of B and T cells
• Usually inherited
• Usually infants die early
 HIV and AIDS

88. HIV and AIDS
 HIV, the human immunodeficiency virus, cripples
the immune system by destroying lymphocytes

89. HIV and AIDS
 AIDS caused by infection with HIV
 HIV kills lymphocytes
• Macrophages, dendritic cells, and helper T cells
• Can get in via certain type of surface receptor
 Diagnostic signs of AIDS
• Severely depressed immune system
• Positive HIV test
• “Indicator disease”- types of pneumonia,
recurrent yeast infections, cancer, drug-resistant
TB

90. Particles bursting the cell membrane

91. HIV Life Cycle
 http://www.youtube.com/watch?v=9leO28ydyfU

92. Pathogens Spread in Four Ways
Infections that can threaten health spread in 4
predictable ways and occur in 4 predictable patterns
1. Direct contact
2. Indirect contact
3. Inhaling pathogens
4. Contact with a vector
 Nosocomial infection: acquired in a hospital

94. Many Infections Are Spread by Contact
or When a Pathogen Is Inhaled

95. Diseases Occur in Four Patterns
 Epidemic
• Disease rate increases to a level above what
we would predict
 Pandemic
• When epidemics break out in several countries
around the world
 Sporadic disease
• Irregularly breaks out and affects relatively few
 Endemic disease
• Occurs more or less continuously

96. Virulence Is a Measure of Pathogen
Damage
 Virulence of a pathogen
 How fast can the pathogen invade the tissues?
 How severe is the damage it causes?
 Which tissues are targeted?

97. Respiratory tract
Preventative measures:
• Hand washing
• Cover mouth when coughing or
sneezing
• Proper disposal of used tissues
• Vaccination programs
GI tract
Preventative measures:
• Hand washing
• Proper food storage, handling, and
cooking
• Good public sanitation (sewage,
drinking water)
Blood
Preventative measures:
• Avoid/prevent needle sharing/ IV drug
abuse
• Maintain pure public blood supplies
• Vaccination programs against blood-
borne pathogens (e. g., hepatitis B)
Skin
Preventative measures:
• Hand washing
• Limit contact with items used by an
infected person
Fig. 9-25a, p. 175

98. The Human Body’s Three Lines of Defense against
Pathogens

99. Introduction to how the immune system
works | Biology | Anatomy | Immunology
 http://www.youtube.com/watch?v=IWMJIMzsEMg

100. Cell Mediated Immune Response
 http://www.youtube.com/watch?v=1tBOmG0QMbA

101. Antibody Mediated Immune Response
 http://www.youtube.com/watch?v=hQmaPwP0KRI