1. Defenses Against Disease: The Immune Response

2. II. Body defenses against invasion
Barriers to entry
1. Skin—a physical barrier
2. Mucous membranes in the respiratory and digestive tracts

3. Figure: 22-01
Title:
Levels of defense against infection.
Caption:

4. Figure: 22-T01
Title:
The cells of the immune response.
Caption:

5. II. Body defenses against invasion
Nonspecific internal defense
1. Macrophages—modified white blood cells engulf and digest microbes by phagocytosis
2. Natural killer cells

6. Figure: 22-01bacterium
Title:
Levels of defense against infection.
Caption:

7. Figure: 22-02
Title:
The protective function of mucus.
Caption:
Mucus traps microbes and debris in the respiratory tract (a brownish-green strand of dirt is shown caught in mucus atop the orange cilia). The cilia lining the walls of the respiratory tract then sweep both mucus and foreign matter out of the body.

8. bacteria entering wound
5 micrometers
wound
skin
bacteria entering wound
bacteria
(c)
white blood cell engulfing bacteria
Figure: 22-03
Title:
The inflammatory response.
Caption:
(a) During an inflammatory response triggered by a cut in the skin, white blood cells squeeze through gaps in the capillary wall and enter the wounded tissue, where they engulf microbes, dirt, and debris from damaged cells. (b) A white blood cell leaving a capillary to join the fray against foreign matter that has entered a cut. (c) A macrophage advances toward a rod-shaped bacterium; this photo was taken on an artificial surface for clarity.
white blood cell
capillary

9. Body defenses against invasion
Nonspecific internal defense:
The Inflammatory Response — a result of injury
Histamine is released from damaged tissue site
1) Weakens capillary walls—become "leaky"
2) Increases blood flow
3) Attracts phagocytotic white blood cells

10. vesicle containing pore-forming protein
natural killer cell
virus
infected cell is killed by the pores
killer cell secretes pore-forming proteins by exocytosis
Figure: 22-04
Title:
How natural killer cells kill their targets.
Caption:
A natural killer cell releases the pore-forming proteins, which assemble to create large holes in the target cell’s plasma membrane. The target cell’s contents leak out, and it dies.
natural killer cell contacts infected cell, releases pore-forming proteins
infected cell
pore-forming proteins insert into the plasma membrane
of the infected cell, self-assembling into large pores

11. Body defenses against invasion
Nonspecific internal defense:
The inflammatory response — a result of injury
b. Blood clots isolate the injury site
c. Fever—an attempt to inhibit bacterial growth
1) White blood cells release pyrogens
a) Raise body temperature set point
b) Increase the body's temperature
c) Decrease iron and zinc concentration in the bloodstream

12. Body defenses against invasion
Specific internal defense:
The Immune Response
1. Lymphocytes mediate the immune response
a. Lymphocytes arise from cells in the bone marrow
b. B cells and T cells
2. Recognition
a. B cells and T cells
1) Antigens
2) Antibodies
3) T cell receptors
b. Antibody specificity and diversity
c. Recognition of foreign antigens, not "self" antigens

13. Body defenses against invasion
Specific internal defense (cont.)
Attacking the invaders: Humoral Immunity
1) Protection against invading organisms
2) B cells with antibodies circulate in the bloodstream
3) Plasma cells mass-produce the required antibody
4) Antibody function
a) Neutralization
b) Promotion of phagocytosis
c) Agglutination
d) Activation of complement reactions

14. Targets: bacteria, exposed viruses, fungi, protists
Antigen from microbe binds B cell antibody and prepares it to divide and differentiate.
antigen
microbe
antibody
Hormone-like chemicals stimulate both B cells and cytotoxic T cells.
B cell
Figure: 22-10humoral
Title:
A summary of humoral and cell-mediated immune responses.
Caption:
A summary of humoral immune responses.
memory B cell
plasma cell
confers future immunity to this antigen
secretes antibodies into the blood and extracellular fluids

15. (a) B cell antibody microbe antigen
Antibody bound to the surface of a B cell recognizes invasion by microbes bearing foreign antigens.
(b)
Figure: 22-06
Title:
Antibodies at work.
Caption:
macrophage
antigen
microbe
antibody
Circulating antibodies bind to antigens on a microbe and promote phagocytosis by a macrophage.

16. antigen binding site antigen light chain variable regions heavy chain
Figure: 22-05
Title:
Antibody structure.
Caption:
Antibodies are proteins composed of two pairs of peptide chains (light chains and heavy chains) arranged like the letter Y. Different antibodies have different variable regions that form unique binding sites.
variable regions
heavy chain
constant
regions

17. Invading antigens bind to antibodies1
Invading antigens bind to antibodies
on one B cell.
antigens 2
The B cell “selected” by antigen multiplies rapidly. 3
A large clone of genetically identical
B cells is produced.
Figure: 22-07
Title:
Clonal selection among B cells by invading antigens.
Caption: 4
B cells
differentiate into plasma cells and memory cells.
plasma
cell
memory
cell

18. Body defenses against invasion
C. Specific internal defense
Attacking the invaders : Cell-mediated defense
1) Protection against infected or cancerous cells
2) Cytotoxic T cells
a) Bind to antigens on the surface of infected cells
b) Release proteins that disrupt the infected cell's plasma membrane

19. Body defenses against invasion
Attacking the invaders:
Cell-mediated defense
3) Helper T cells
a) Release interleukins
b) Promote formation of B cells and cytotoxic T cells
c) Create long-term memory cells
4) Suppressor T cells
a) Suppresses continued immune response after infection

20. Targets: virus-infected cells, cancel cells, transplants
foreign antigens presented on surface of macrophage and infected cell
macrophage
infected cell
helper T cell
Hormone-like chemicals stimulate both B cells and cytotoxic T cells.
T cell receptor binds foreign antigen and stimulates T cell to
release chemicals.
Chemicals stimulate formation of memory T cells.
Figure: 22-10cell
Title:
A summary of humoral and cell-mediated immune responses.
Caption:
A summary of cell-mediated immune responses.
cytotoxic T cell
memory T cell
confers future immunity to this antigen
releases pore-forming proteins that destroy infected cells

21. Body defenses against invasion
Specific internal defense:
Immunologic Memory
a. B and T memory cells survive many years
b. Memory cells activate a quicker second defense against the same invader

22. foreign antigens presented on surface of macrophage and infected cell
Targets: bacteria, exposed viruses, fungi, protists
Targets: virus-infected cells,
cancer cells, transplants
foreign antigens presented
on surface of macrophage
and infected cell
Antigen from microbe binds B cell antibody and prepares it to divide and differentiate.
macrophage
infected cell
antigen
microbe
antibody
helper T cell
Hormone-like chemicals stimulate both B cells and cytotoxic T cells.
T cell receptor binds foreign antigen and stimulates T cell to release chemicals.
B cell
Chemicals stimulate formation
of memory T cells.
Figure: 22-10
Title:
A summary of humoral and cell-mediated immune responses.
Caption:
cytotoxic T cell
memory T cell
plasma cell
memory B cell
confers future immunity to this antigen
confers future immunity to this antigen
secretes antibodies into the blood and extracellular fluids
releases pore-forming proteins that destroy infected cells

23. Medicine and the immune response
A. Antibiotics combat infection by slowing down microbial reproduction
B. Vaccinations—injections of weakened or killed microbes stimulate development of memory cells
C. Allergies and the immune response
D. Autoimmune diseases—"anti-self"

24. hybrid human-bird virus forms in pig and may infect people
human virus
RNA strands
Figure: 22-E22_01A
Title:
Formation of deadly new strains of influenza.
Caption:
(a) Recombination of genes from bird and human flu viruses, which occurs rarely, can result in deadly new strains of flu.
hybrid human-bird virus forms in pig
and may infect people
bird virus

25. “Allergy” plasma cell releases “allergy” antibodies.
binding site for “allergy antibodies”
vesicle containing histamine
mast cell
allergy antibodies bind
Figure: 22-11
Title:
Allergic reactions.
Caption:
Pollen grains enter respiratory tract.
Pollen binds to allergy antibodies, causes histamine release.
Histamine causes allergy symptoms.

26. Medicine and the immune response
E. Immune deficiency diseases
1. SCID—severe combined immune deficiency

27. Medicine and the immune response
Immune deficiency diseases
2. AIDS—acquired immunodeficiency syndrome
a. The HIV retroviruses infect host helper T cells
b. Mechanisms of HIV transmission
c. Incidence of AIDS
d. Treatments of AIDS
1) Reverse transcriptase inhibitors
2) Protease inhibitors
3) AIDS vaccine research
e. AIDS prevention
f. AIDS, research funding, politics, and the media

28. envelope (lipid bilayer) (a)
glycoproteins
envelope (lipid bilayer)
(a)
protein coat
spikes
core proteins
(b)
reverse transcriptase
viral RNA coated with protein
Figure: 22-12
Title:
The virus that causes AIDS.
Caption:
(a) HIV consists of an outer envelope, a protein coat, and an inner protein capsule that contains RNA and reverse transcriptase. Proteins protruding through the envelope attach to the plasma membranes of helper T cells. (b) The red specks in this colorized scanning electron micrograph are HIV that have just emerged from the large, green helper T cell. (c) In this colorized transmission electron micrograph, HIV are emerging from the helper T cell and acquiring an outer envelope of plasma membrane (green) from the infected T cell.
(c)

29. III. Medicine and the immune response
Cancer
1. Malfunctioning of the growth controls of the body's own cells
a. Benign tumors
b. Malignant tumors
Cancer treatments
a. Distinguishing cancer cells from normal body cells
b. Surgery
c. Radiation
d. Chemotherapy
e. Experimental gene therapy

30. Major Histocompatability Complex Antigens are always presented in association with either of two related classes of proteins. These proteins are coded by genes located together on a small stretch of one chromosome. They are critical in determining whether a transplant will be rejected, so they are called major histocompatibility complex (MHC) class I and class II proteins or antigens. They are structurally related to each other and to immunoglobulins (left part of figure), so they are considered members of the immunoglobulin superfamily.

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 At question is MHC - Major Histocompatibility Complex. That's an extremely high-falutin' phrase that points to a very specific gene soup that exists in every critter with a backbone. MHC does all sorts of things - most notably, they regulate the immune function of the host body to different types of diseases, and effect the body’s acceptance or rejection of transplanted cells. They decide what your Body Odor smells like. And, according to science, they might also decide who you want to make babies with.