1. NOTES: Specific Defenses / Immunity (UNIT 10 part 3)

2. ANTIGENS…
• ANTIGENS: specific foreign molecules that trigger an immune response; usually located on a cell’s surface
-antigens include:
proteins glycoproteins
polysaccharides glycolipids
toxins (venom, produced by bacteria)

3. ANTIGENS…
• lymphocytes (B and T cells) develop receptors during embryonic development that allow them to distinguish between nonself (foreign) and self antigens

4. Notice the receptors look identical for the B and T cell.
DURING EMBRYONIC DEVELOPMENT…
Notice the receptors look identical for the B and T cell.

5. ANTIGENS…
• nonself antigens combine with T cell and B cell surface receptors and activate these cells; this begins a specific immune reaction (your 3rd line of defense)

7. REVIEW QUESTION:
What was the generic anatomical term for “white blood cell?”
Erythrocyte
Lymphocyte
Leukocyte
Fibroblast

8. LYMPHOCYTES (T and B Cells)
• originate in the red bone marrow
• some are released into the blood before they differentiate (specialize)
-these reach the THYMUS, where they mature into
T CELLS
• others, the B CELLS, mature in the RED BONE MARROW
• both T cells and B cells reside in lymphatic tissues and organs (lymph nodes, spleen, etc.)

9. LYMPHOCYTE FUNCTIONS
**a lymphocyte must be ACTIVATED before it can respond to an antigen**

11. Activating the 3rd Line of Defense:
1st line and 2nd line of defenses have failed
As part of 2nd line of defense, macrophages and dendritic cells have engulfed and destroyed pathogen
Parts of the pathogen (antigen) move to the surface of the phagocytic cell
Called antigen presentation

12. Activating the 3rd Line of Defense:
When phagocytic cell
randomly bumps into correct/
matching Helper T-cell, this
activates the Helper T-cell

13. T CELLS and the CELLULAR IMMUNE RESPONSE
Activated Helper T-cell divides into an army of Helper T-cell clones
antigen
T cell!
Antigen
Presenting
Cell
(APC)

14. T-CELLS
● Helper T-cells secrete chemicals that enhance cellular response to antigens
Cause other T-cells and B-cells to divide and/or produce more chemicals
“army” of TH move through circulatory & lymphatic system
These chemicals and the antigen activate the specific Cytotoxic T-cell

15. T-CELLS
● Cytotoxic T-cells interact with and destroy the cells of your body that are infected (ex: throat cells invaded by cold virus)
CELLULAR RESPONSE
● Cytotoxic T-cells secrete toxins (PERFORIN) that cause the cell to burst (lyse) which kills infected body cells  this destroys bacteria and immature viruses inside

16. T-CELLS
● Like macrophages, your infected body cells will also present antigen but Cytotoxic T-cells can tell the difference between an infected body cell & a macrophage presenting antigen
-recognize nonself antigens on cancer cells or virus- infected cells

17. B-CELLS
● specific B-cell also needs to be activated by the specific Helper T-cells
● Once the specific Helper T-cell randomly bumps into the specific B-cell, contact and chemicals will activate the correct B-cell  B-cells divide into clones!
HUMORAL IMMUNE RESPONSE
● activated B-cell (called a plasma cell) will produce
antibodies & memory cells
for later

19. ● activated B cells specialize into PLASMA CELLS (antibody-producing cells)
*(antibodies react against the antigen that stimulated their production)
AND
● activated B cells also differentiate into MEMORY B CELLS (respond to subsequent exposures of the same antigen)

21. T and B cells…
**each person has millions of varieties of T and B cells BUT only a few of each variety (receptor shape)
**once a specific cell has been activated, that cell CLONES itself to make lots of copies of the correct antigen fighting cell**
**Therefore, each type of T cell or B cell has a particular type of antigen receptor that can respond only to a SPECIFIC antigen**

23. REVIEW QUESTION: What cellular process results in clones? Mitosis
Meiosis
Mutation
Fragmentation

24. TYPES OF ANTIBODIES
● antibodies are proteins called IMMUNOGLOBULINS (Ig)
● 5 major types or classes of antibodies: IgG, IgA, IgM, IgD, and IgE.

25. IgG

26. ANTIBODY ACTIONS ● antibodies work by:
attacking the antigens directly (attaching to antigen)
-cause them to clump together (AGGLUTINATION) or form insoluble masses (PRECIPITATE)
-makes it easier for phagocytes to engulf the antigens / antigen-bearing agents & eliminate them

28. Agglutination

30. ANTIBODY ACTIONS
2) stimulate changes in local areas that help prevent the spread of the antigens
(ex: promote inflammation)

31. REVIEW QUESTION: The humoral response involves
B cells, Cytotoxic T cells, and antibodies
B cells, and antibodies
Cytotoxic T cells and perforin
B and C

32. REVIEW QUESTION: The function of Helper T-cells is to
Produce antibodies
Engulf and destroy pathogens
Destroy infected cells
Activate both the cellular response & humoral response

33. REVIEW QUESTION:
Which of the following are antigen presenting cells (APC)?
Infected body cell
Body cell that has become cancerous
Macrophage that has engulfed & destroyed a pathogen
All of the above are antigen presenting cells

34. REVIEW QUESTION:
A B-cell that has been activated will undergo mitosis and make clones of itself. What happens to some of those B-cells next?
They differentiate into a plasma cell and make antibodies
They start releasing perforin to destroy infected cells
They are selected for destruction
They move into the bloodstream and release antigen