1. Immune System
A&P II

2. Lymphatic Outline Lymphatic System Defense Systems Immunodeficiencies
Innate Immune System
Adaptive Defense System
Immunodeficiencies
Immune Responses

3. Lymphatic System: Overview
Figure 21.1a, b

4. Lymphatic Capillaries & Transport
Absorbtive role during inflammation
Lymph nodes
The lymphatic system lacks an organ that acts as a pump
Uses the some of the same methods as veins to propel lymph

5. Lymphocytes T cells and B cells protect the body against antigens
Antigen – anything the body perceives as foreign
T cells
B cells

6. Other Lymphoid Cells
Macrophages
Dendritic cells
Reticular cells

7. Lymph Node

8. Other Lymphoid Organs

9. Spleen

10. Thymus

11. Tonsils

12. Immune System Outline Innate Immunity Adaptive Immunity
Cells & Chemicals
Phagocytosis
Inflammation
Adaptive Immunity
Humoral Immunity
Cells
Humoral Response
Antibodies
Memory
Cell-Mediated Immunity
Antigen Recognition
MHC Proteins
T-Cells
Cytokines
Organ Transplants
Immunodeficiency's
Autoimmune Conditions

13. Immunity: Two Intrinsic Defense Systems
Innate Immune System
Non-specific Immune System
Adaptive defense system
Specific Immunity

14. Innate Immunity
Skin, mucous membranes, and their secretions make up the first line of defense
Keratin
Epithelial Membranes

15. Innate Immunity: Cells and Chemicals
Specific Cell Types

16. Mechanism of Phagocytosis

17. Innate Immunity: Cells and Chemicals
Specific Cell Types

18. Innate Immunity: Cells and Chemicals
Specific Cell Types
Inflammation

19. Inflammatory Response
The inflammatory response is triggered whenever body tissues are injured
Stages
Vasodilation and Increased Vessel Permeability
Phagocyte Immigration
Tissue Repair
The four cardinal signs of acute inflammation are redness, heat, swelling, and pain

20. Inflammatory Response: Vasodilation & Edema
Begins with a flood of inflammatory chemicals released into the extracellular fluid
Toll-like receptors (TLRs)
Inflammatory mediators
Include histamine, kinins, prostaglandins (PGs), complement, and cytokines
Edema

21. Inflammatory Response: Phagocytic Mobilization
Four Phases:
Leukocytosis
Margination
Diapedesis
Chemotaxis

23. Abscess & Pus If infection is severe  develop pus
Sac of pus can be walled off forming an abscess
Infectious granulomas can form

24. Antimicrobial Proteins
Enhance the innate defenses by:
Two important antimicrobial proteins are:
Interferon
Complement proteins

25. Interferon (IFN)
Genes that synthesize IFN are activated when a host cell is invaded by a virus
Interferon molecules leave the infected cell and enter neighboring cells
IFN stimumulates the neighboring cells to produce antiviral proteins
and fever, are related to the production of IFNs during infection.

26. Complement
20 or so proteins that circulate in the blood in an inactive form
Provides a major mechanism for destroying foreign substances in the body
Amplifies all aspects of the inflammatory response
Enhances the effectiveness of both nonspecific and specific defenses

27. Fever
Abnormally high body temperature in response to invading microorganisms
The body’s thermostat is reset upwards in response to pyrogens
High fevers are dangerous as they can denature enzymes
Moderate fever can be beneficial

28. Specific (Adaptive) Defenses
Bodies built in defense system
Must be primed by an initial exposure to an antigen
The adaptive immune system is a functional system that:
Recognizes specific foreign substances
Is systemic
Has memory

29. Adaptive Immunity: Summary
Two-fisted defensive system that uses lymphocytes, APCs, and specific molecules to identify and destroy nonself particles
Its response depends upon the ability of its cells to:
Recognize foreign substances by binding to them
Communicate with one another so that the whole system mounts a response specific to those antigens

30. Specific Immune Defenses
It has two separate but overlapping arms
Humoral, or antibody-mediated immunity
Provided by antibodies that circulate freely
Cellular, or cell-mediated immunity
Protective factor is lymphocytes
Targets are cellular
Helper & Direct Killing

31. Antigens (Ags)
Substances that can mobilize the immune system and provoke an immune response
The ultimate targets of all immune responses are mostly large, complex molecules not normally found in the body
Important functional properties:
Complete antigens
Haptens

32. Self-Antigens: MHC Proteins
Our cells are dotted with protein molecules that are not antigenic to us but are strongly antigenic to others
One type of these, major histocompatability complex (MHC) proteins, mark a cell as self
Two classes of MHC proteins

33. Cells of the Specific Immune System
Two types of lymphocytes
B lymphocytes
T lymphocytes
Cytotoxic T-cells
Helper T-cells
Antigen-presenting cells (APCs):
Do not respond to specific antigens

34. Immunocompetent B or T cells

35. Immunocompetent B or T cells
Figure 22.8

36. Lymphocytes
Figure 22.7

37. Antigen-Presenting Cells (APCs)
Major rolls in immunity are:
To engulf foreign particles
To present fragment of antigens on their own surfaces, to be recognized by T cells
Major APCs
Macrophages
Dendritic cells
Langehrans cells
Activated B cells

38. Humoral Immunity Response
Antigen challenge
If the lymphocyte is a B cell:
The challenging antigen provokes a humoral immune response

39. Clonal Selection
Figure 22.9

40. Figure 18.14

41. Antibodies (Ab)

42. Antibody Structure
Figure 22.12

43. Classes of Antibodies
IgD – monomer attached to the surface of B cells,
IgM – pentamer released by plasma cells during the primary immune response
IgG – monomer that is the most abundant and diverse antibody in primary and secondary response
IgA – dimer that helps prevent attachment of pathogens to epithelial cell surfaces
IgE – monomer that binds to mast cells and basophils

44. Thought Question
Why would you administer gamma globulin to patients suffering from specific diseases (ex. Hepatitis)?

45. Immunological Memory
Figure 22.10

46. Acquired Immunity
Figure 22.11

47. Thought Question
Why is vaccine development for certain viral diseases, (dengue fever, HIV, Ebola) difficult?
What was the first disease that a vaccine was developed for?

48. Mechanisms of Antibody Action
Figure 22.13

49. Cell-Mediated Immune Response
Two major populations of T cells mediate cellular immunity
CD4 cells (T4cells) are primarily helper T cells (TH)
CD8 cells (T8cells) are cytotoxic T cells (TC) that destroy cells harboring foreign antigens
Other types of T cells are:
Delayed hypersensitivity T cells (TDH)
Suppressor T cells (TS)
Memory T cells

50. Antigen Recognition

51. MHC Proteins
Both types of MHC proteins are important to T cell activation
Class I MHC proteins
Always recognized by CD8 (cytotoxic) T-cells
Display peptides from endogenous antigens

52. Class I MHC Proteins
Figure 22.14a

53. Class II MHC Proteins
Class II MHC proteins
Exogenous Antigens

54. Class II MHC Proteins
Figure 22.14b

55. Thought Question
Why is it important to try to get a good MHC match prior to an organ transplantation?

56. T-cell Activation
Antigen Binding
Costimulation

57. Figure 18.18

58. Figure 18.18

59. Cytokines Chemical mediators that enhance the immune response
Some are costimulators of T cells and T cell proliferation
Interleukin 1 (IL-1) released by macrophages costimulates bound T cells to:
Release interleukin 2 (IL-2)
Synthesize more IL-2 receptors

60. TH – Helper T-cells

61. Helper T Cells

62. Cytotoxic T Cells (TC)
TC cells, or killer T cells, are the only T cells that can directly attack and kill other cells
They circulate throughout the body in search of body cells that display the antigen to which they have been sensitized

63. Mechanisms of TC Action
In some cases, TC cells:
Bind to the target cell and release perforin into its membrane
Figure 22.17a

64. Mechanisms of TC Action
Other TC cells induce cell death by:
Secreting lymphotoxin
Releasing tumor necrosis factor (TNF)
Secreting gamma interferon

65. Summary Table

66. Organ Transplants Autografts Isografts Allografts Xenografts
ABO & blood group antigens must match
MHC antigen match
Xenografts

67. Immunodeficiencies
Congenital and acquired conditions in which the function or production of immune cells, phagocytes, or complement is abnormal
SCID – severe combined immunodeficiency (SCID) syndromes; genetic defects that produce:
SCID is fatal if untreated; treatment is with bone marrow transplants

69. Acquired Immunodeficiencies
Hodgkin’s disease – cancer of the lymph nodes leads to immunodeficiency by depressing lymph node cells
AIDS – Acquired Immune Deficiency Syndrome

70. Thought Questions
Which cells does AIDS target that causes individuals to become susceptible to opportunistic infections?
Is there another disease that caused the body to become susceptible to opportunistic infections?

75. Autoimmune Diseases
Loss of the immune system’s ability to distinguish self from nonself
Examples include
Multiple sclerosis,
Myasthenia gravis
Graves’ disease
Type I (juvenile) diabetes mellitus
Systemic lupus erythematosus (SLE)
Glomerulonephritis
Rheumatoid arthritis

76. Hypersensitivity Immune responses that cause tissue damage
Immune complex-mediated allergies are immediate and subacute hypersensitivities

77. Immediate Hypersensitivity
Reactions include runny nose, itching reddened skin, and watery eyes
Antihistamines counteract these effects

78. Systemic Response: Anaphylactic Shock
Immediate Hypersensitivity
Systemic Response: Anaphylactic Shock
Response to allergen that directly enters the blood (e.g., insect bite, injection)
Systemic histamine releases may result in:
Constriction of bronchioles
Sudden vasodilation and fluid loss from the bloodstream
Hypotensive shock and death

79. Immune-Complex Hypersensitivity
Antigens are widely distributed through the body or blood
Insoluble antigen-antibody complexes form
Intense inflammation, local cell lysis, and death may result

80. Delayed Hypersensitivities
Onset is slow (1–3 days)
Mediated by mechanisms involving delayed hypersensitivity T cells (TDH cells) and cytotoxic T cells (TC cells)
Cytokines from activated TC are the mediators of the inflammatory response

82. Immune System Outline Innate Immunity Adaptive Immunity
Cells & Chemicals
Phagocytosis
Inflammation
Adaptive Immunity
Humoral Immunity
Cells
Humoral Response
Antibodies
Memory
Cell-Mediated Immunity
Antigen Recognition
MHC Proteins
T-Cells
Cytokines
Organ Transplants
Immunodeficiency's
Autoimmune Conditions