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Chapter 23 Immune Systems. 4. Immune 1 adj. Derived from classical Latin Munia = duties 1. Exempt from something disagreeable or harmful 2. Not susceptible to some specified disease. 12. What can make you sick?. Cutting board Bacteria and Fungi, 300x 2. Legionella bacteria 3000x 2.

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Chapter 23 immune systems

Chapter 23 Immune Systems



adj. Derived from classical Latin

Munia = duties

1. Exempt from something disagreeable or harmful

2. Not susceptible to some specified disease


What can make you sick
What can make you sick?

Cutting board Bacteria and Fungi, 300x2

Legionella bacteria


Anthrax Bacteria


Anthrax spores in lung


Ragweed Pollen, 550x2

Polio Virus, 46,050x 2

The disease process

1. Infection byPathogen

Infection: Entry of pathogen into the body

Pathogen: Any foreign body that can cause disease

2. Disease

When the body’s cells and tissues have been damaged by the pathogen so that they no longer function

The Disease Process


Patho = suffering (Greek, Latin)

gen = producing (Latin)


In = in (Latin)

fect = to do or make (Latin)

Antigen = Any foreign material that activates the immune system; usually a protein. Need not be pathenogenic.

Why is an antigen called an antigen? See P. 604

How does the immune system prevent disease

Nonspecific Defenses


Eg. Skin, bark, mucous membranes, low pH of stomach, antibacterial enzymes in sweat, tears, saliva



Specific Defenses (Adaptive Immunity)

Develops in 4-14 Days

Cell mediated response

Antibody mediated response

Memory cells

How does the immune system prevent disease?

Resistance = “the ability to ward off infectious diseases” (447)

What’s fever for?



Nonspecific defenses


Phagocytic cells have special cell surface receptors which recognize antigens

Also recognize self

Engulf and destroy foreign bodies

Activate specific defenses


Response to injury, damage, or foreign antigens

Damaged capillaries leak fluid and cells into injury

Redness, swelling, warmth

Phagocytes remove debris and dead cells

Nonspecific Defenses

Pus = Phagocytic cells, dead pathogens, debris

Alveolar macrophage phagocytosis of E. coli; 1315x 2

Internal nonspecific defenses

Internal Nonspecific Defenses

White blood cells

Defensive proteins


NK cells


Complement proteins

  • Engulf foreign cells or substances

  • Destroy infected body cells

  • Protect body cells against viral infection

  • Cause invading cells to lyse



Figure 24.4

Internal Nonspecific Defenses

The first line of defense 19
The First Line of Defense19


P.S. The nail was driven into that person’s hand by a nail gun. OUCH!

Who am i 13
Who am I?13

HLA = Human Leukocyte Antigen

The cell “name tag” or “fingerprint

Each “flag” is a protein displayed on the cell’s surface.

Except in unusual cases or identical twins, a person’s combination of HLA factors is unique

Specificity: Immune system is NOT supposed to react to self HLA, but IS supposed to react to everything else.

Macrophages as gatekeepers 23
Macrophages as Gatekeepers23

  • Macrophages recognize and engulf any particle virus or cell that does not carry the “self” HLA protein code on its surface.

  • Then, they display the antigen on their surface using their MHC molecules.

Immunity through leukocytes 2

White blood


to the rescue!

Immunity through Leukocytes2

Blood with T Cells and Platelets; 2000x

Macrophage; 950x

Neutrophils; 1000x

Helper T cell (small cell) and B cell (large cell); 2000x

Remember… we need specificity and memory!

Lymphocytes a kind of leukocyte


Lymph nodes

Lymphatic vessels, entering veins




Bone marrow

Lymphatic vessels

Lymphocytesa kind of leukocyte

2 Trillion in your body

Originate in bone marrow

  • Mature in Primary Lymph Tissues

    • Thymus (T Cells)

    • Bone Marrow (B Cells)

  • Collect in Secondary Tissues

    • Lymph nodes

    • Spleen

    • Tonsils

    • Appendix

  • Circulate in Lymph and Blood Vessels (via Thoracic Duct)

Look at P. 609

Figure 24.7

Adaptive immunity

B Lymphocyte

from bone marrow (bursa)

Produce antibodies

“Against antigen”

Antibody mediated (Humoral)

immune response

T Lymphocyte

from thymus

Recognize antigens on pathogens

Cell mediated

immune response

Adaptive Immunity

Helper T cell (small cell) and B cell (large cell); 2000x 2

Immune Surveillance: Both have receptors on their membranes to recognize antigens and travel through the body to “seek out and destroy.”

Leukocyte production 3
Leukocyte Production3

The point is thatstem cellscan turn into many different kinds of leukocytes!

T Cells need further development in the Thymus, B cells mature in the Bone marrow

Cell mediated immunity and t lymphocytes 2

Helper T Cells (TH)

Secrete cytokines

Stimulate the production of antibodies by B cells

Cytotoxic T Cells (CTL)

Attack foreign cells

Attack infected “self” cells

Suppressor T Cells

Shut down the immune system

Reduce B and T cell activities

Memory T Cells

Cell Mediated Immunity and T Lymphocytes2

Activated by Antigen display by macrophages

Activation of t cells 19
Activation of T Cells19

Antigen fragments activate Helper and Cytotoxic T cells.

Helper t cells at the center 24
Helper T Cells at the Center24

Macrophage displays antigen


APC stimulates the Helper T cell

Cytotoxic T Cells and B cells both need the cytokines of the Helper T cells to become active

Ctls at work 24
CTLs at Work24

After activation by TH cellsT-Cells destroy

~ non-self cells ~ altered or infected self cells

Antibody mediated immunity and b lymphocytes 3

1. B Cell receptors bind to an antigen

2. B Cell digests and displays a “ready” complex

3a. Helper T Cell recognizes complex and produces lymphokines

3b. Rapid mitosis occurs

Plasma cells make antibodies

Memory cells last a long time. Can make antibodies and more plasma cells.

Antibodies bind to antigen to mark it for destruction

Antibody Mediated Immunity and B Lymphocytes3

So what is this thing called an antibody 3


4 polypeptides held together with disulfide bonds

Each B cell makes only one kind

Each kind binds one antigen

~106 different kinds

So, what is this thing called an Antibody?3


Antibody antigen binding 14

Each antibodybinds one antigenin a lock and key arrangement

Remember enzyme-substrate fit.

Antibody-Antigen Binding14

Variable Region


Complement Binding Site

Clonal selection theory 3
Clonal Selection Theory3

Remember… Each B cell only makes one antibody

So how is the immune response specific?

Antibodies in action 5

Antibodies bind to antigens making it easier for macrophages to surround and destroy

Binding of complement proteins to antibody also enhances phagocytosis

Antibodies in Action5

Antibodies and complement 8

1. Antibodies bind antigen

2. Binding activates complement proteins

3. Those complement proteins activate others

4. Complement proteins “drill” holes in microbe membrane (lyse cells), letting fluid pressure burst the cell

Activated complement also stimulates inflammation

Antibodies and Complement8





Antibody diversity 3
Antibody Diversity3

  • Each antibody needs

    • 1 kind of light chain

    • 1 kind of heavy chain

  • There is DNA recombination involved to produce22

    • 7500 kinds of light chains

    • 2.4 million kinds of heavy chains

7500 x 2.4 million = 18 billion possible kinds of antibodies!

Categories of immunity 9

Primary Immune Response

After initial exposure to antigen

7-14 days

Stimulates specific B cells that respond to the antigen/pathogen

Secondary Immune Response

Subsequent exposure

2-6 days

Memory cells immediately begin dividing to produce plasma cells (B cells)

Antibody production begins more quickly

1st Exposure

Amount of Antibody

1st Exposure

2nd Exposure

Time (days)

Categories of Immunity9

Look at speed of response and amount of antibody produced the second time!

When the system doesn t work right

Cell or antibody mediated

Chemical change in cell surface proteins

Cells no longer recognized as self

Immune system attacks those cells

See p. 624

Eg. Poison Ivy Reaction

Cell mediated

Cell destruction causes swelling, redness, blisters

When the system doesn’t work right

Hypersensitive Immune Systems


Also read about diseases and chemicals…



Hypersensitive Immune Systems




Autoimmunity 15

Autoimmune Diseases

Immune system stops recognizing self HLA

Immune system attacks the body’s own cells

Caused by

Genetic susceptibility



Immune system memory and vaccinations


from Latin

Vacca = cow

ation =action or process

Generally only works for one specific disease

Edward Jenner (1798)

Cowpox exposure

Immune system remembers the cowpox

Vaccinated personimmune to smallpox

Last smallpox deaths occurred in 1978

Immune System Memory and Vaccinations


Will the smallpox vaccine protect against other viruses?


The last known person in the world to have smallpox of any kind. Here 23-year-old Ali Maow Maalin of Merka, Somalia exhibits the pox of Variola minor.7

Kinds of immunity 18


from reaction of immune system with antigen


fetus/newborn gets antibodies directly from mother, in colostrum/milk


from vaccination


from direct injection of antibodies

Kinds of Immunity18

Which ones do you have NOW?

Literature cited
Literature Cited

Cool Web Sites: IIR/IIRimsys.htm, staff/hand/Warriorsimm.htm ----- This is cartoons! ----- antibody.htm

Macrophage Epitope Display:

1. Immunity: Webster’s New World Dictionary and Thesaurus, 1996.

2., with permission.

3. Leukocyte Production, B Cell and Macrophage activation, antibody schematic, clonal selection: http://


5. Macrophage ingesting bacteria covered with antibody:



8. Complement:

Cites cont
Cites, cont.

9. Immune Response Graph: part1/lec05/lec6_99.html

10. Poison Ivy Picture:

11. Poison Ivy Face 1:


13. HLA:

14. Antibody graphics/epitope.gif

15. Autoimmune Diseases: autoimmune/autoimmune.htm

16. Histamine Structure:

17. Allergy Diagram:

18 images/hiv-vaccine.jpg

19. BioCD. From Biology, Fifth Edition. Campbell, Reece, Mitchell. Addison, Wesley, Longman. 1999.


21. handsafe.html



24. Bioshow: for Biology: Concepts and Connections, Second Edition. Campbell, Mitchell, and Reece