1. Chapter 43 Warm-Up Define the following terms:
Pathogen
Antigen
Antibody
Allergen
Vaccine
What are lymphocytes? Where do B cells and T cells mature?

2. Ch. 43 Review Warm-Up
What is the difference between innate vs. adaptive immunity?
Contrast the functions of B cells and T cells.
How are antigens recognized by immune system cells?
What are memory cells?
How does HIV affect the immune system?

3. Chapter 43
THE IMMUNE SYSTEM

4. What you must know: Several elements of an innate immune response
The differences between B and T cells relative to their activation and actions.
How antigens are recognized by immune system cells
The differences in humoral and cell-mediated immunity
Why Helper T cells are central to immune responses

5. Types of Immunity Innate Immunity Adaptive Immunity Non-specific
All plants & animals
Pathogen-specific
Only in vertebrates
Involves B and T cells

6. Plant Defenses Nonspecific responses Receptors recognize pathogen
Thicken cell wall, produce antimicrobial compounds, cell death
Localize effects

7. Pathogens (such as bacteria, fungi, and viruses)
Figure 43.2
Pathogens (such as bacteria, fungi, and viruses)
INNATE IMMUNITY (all animals)
Barrier defenses:
Skin Mucous membranes Secretions
Recognition of traits shared by broad ranges of pathogens, using a small set of receptors •
Internal defenses:
Phagocytic cells Natural killer cells Antimicrobial proteins Inflammatory response
• Rapid response
Figure 43.2 Overview of animal immunity.
ADAPTIVE IMMUNITY (vertebrates only)
Humoral response:
Antibodies defend against infection in body fluids.
Recognition of traits specific to particular pathogens, using a vast array of receptors •
Cell-mediated response:
Cytotoxic cells defend against infection in body cells.
• Slower response

8. Innate Immunity Antimicrobial Proteins: Barrier Defenses:
Interferons (inhibit viral reproduction)
Complement system (~30 proteins, membrane attack complex)
Barrier Defenses:
Skin
Mucous membranes
Lysozyme (tears, saliva, mucus)
Innate Immunity
(non-specific)
Natural Killer Cells:
Virus-infected and cancer cells
Inflammatory Response:
Mast cells release histamine
Blood vessels dilate, increase permeability (redness, swelling)
Deliver clotting agents, phagocytic cells
Fever
Phagocytic WBCs:
Neutrophils
Macrophage (“big eaters”)
Eosinophils (parasite destroyers)
Dendritic

9. Phagocytosis

10. Inflammatory Response

11. Lymphatic System: involved in adaptive immunity

12. Adaptive Immunity
Lymphocytes (WBCs): produced by stem cells in bone marrow
T cells: mature in thymus
helper T, cytotoxic T
B cells: mature in bone marrow
plasma cells make antibodies

13. Adaptive Immunity
1. humoral immune response: antibodies help neutralize or eliminate pathogens in the blood and lymph
2. cell-mediated immune response specialized T cells destroy affected host cells by apoptosis
*BOTH are triggered by the helper T cells
*BOTH make memory cells

14. Antigen: substance that elicits lymphocyte response
Antibody (immunoglobulin – Ig): protein made by B cell that binds to antigens

15. B cells that differ in antigen specificity Antigen Antigen receptor
Figure 43.14
B cells that differ in antigen specificity
Antigen
Antigen receptor
Figure Clonal selection.
Antibody
Memory cells
Plasma cells

16. Major Histocompatibility Complex (MHC)
Proteins displayed on cell surface
Responsible for tissue/organ rejection (“self” vs. “non-self”)
B and T cells bind to MHC molecule of antigen presenting cell in adaptive response

17. Cytokines are chemical signals that attract B and T cells
Antigen- presenting cell
Antigen fragment
Pathogen
Class II MHC molecule 1
Accessory protein
Antigen receptor
Helper T cell 
Cytokines 
Figure The central role of helper T cells in humoral and cell-mediated immune responses. 2
Cell- mediated immunity
Humoral immunity   3
B cell
Cytotoxic T cell

18. Cell-Mediated Immune Response Humoral Immune Response
Antigen-presenting cell
Cell-Mediated Immune Response
(T Cells)
Humoral Immune Response
(antibodies)
Helper T cell
B cell
Cytotoxic T cell
Plasma cell
tag for destruction
Identify and destroy
Infected cell
Antibodies

19. Proliferation of B and T cells
Once activated: B or T cell divides to produce clones
1. effector cells that act immediately against the antigen
2. memory cells make effector cells if the same antigen is encountered again

20.  1 2 3 Antigen-presenting cell Pathogen Antigen fragment B cell
Figure
Antigen-presenting cell
Pathogen
Antigen fragment
B cell
Class II MHC molecule
Memory B cells 
Accessory protein
Cytokines
Antigen receptor
Figure Activation of a B cell in the humoral immune response.
Activated helper T cell
Helper T cell
Plasma cells
Secreted antibodies 1 2 3

21. Cytotoxic T cells destroy infected cells with Perforin (creates pores)
Released cytotoxic T cell
Accessory protein
Antigen receptor
Dying infected cell
Perforin
Class I MHC molecule
Gran- zymes
Pore
Infected cell
Figure The killing action of cytotoxic T cells on an infected host cell.
Antigen fragment 1 2 3

22. Immunological Memory Primary immune response: 1st exposure to antigen
Memory cells:
Secondary immune response: repeat exposure  faster, greater response

23. Histamine IgE Allergen Granule Mast cell Figure 43.22
Figure Mast cells, IgE, and the allergic response.
Granule
Mast cell

24. Passive immunity: via antibodies in breast milk
Immunizations/vaccines: induce immune memory to nonpathogenic microbe or toxin
Passive immunity: via antibodies in breast milk
Allergies: hypersensitive responses to harmless antigens
Autoimmune Diseases:
Lupus, rheumatoid arthritis, Type I diabetes, multiple sclerosis
HIV: infect Helper T cells
AIDS = severely weakened immune system

25. Helper T cell concentration (in blood (cells/mm3)
Figure 43.25
Latency
AIDS
Relative anti-HIV antibody concentration
800
Relative HIV concentration
600
Helper T cell concentration (in blood (cells/mm3)
Helper T cell concentration
400
Figure The progress of an untreated HIV infection.
200 1 2 3 4 5 6 7 8 9 10
Years after untreated infection

26. Blood Groups
Antigens on red blood cells determine whether a person has blood type A (A antigen), B (B antigen), AB (both A and B antigens), or O (neither antigen)
Antibodies to nonself blood types exist in the body
Transfusion with incompatible blood leads to destruction of the transfused cells
Recipient-donor combinations can be fatal or safe
© 2011 Pearson Education, Inc.

27. Cancer and Immunity
The frequency of certain cancers increases when adaptive immunity is impaired
20% of all human cancers involve viruses
The immune system can act as a defense against viruses that cause cancer and cancer cells that harbor viruses
In 2006, a vaccine was released that acts against human papillomavirus (HPV), a virus associated with cervical cancer
© 2011 Pearson Education, Inc.