Review: Cell Mediated and Humoral Immunity ---------Humoral Immunity

Question 1

1. What is the main lymphocyte cell in this branch of the immune system?

Answer 1

Main cell: B-cell

Question 2

2. Is Antigen material presented to Immunocompetent B-cell as in cell mediated immunity?

Answer 2

Immunocompetent B-cell “bumps” into free Ags released into to lymph node (3-4 days)

Question 3

3. Where are Ab receptors located on B- cells?

Answer 3

Ab receptors on B-cell surface combine with free Ag

Question 4

4. Are Ab receptors already genetically primed before a B-cell ever encounters antigen?

Answer 4

Yes

Question 5

5. How do B-cells recognize Ag? (free or in an MHC receptor)

Answer 5

Free antigen

Question 6

6. What is capping?

Answer 6

Ab-Ag complexes move to one area of B-cell surface : Capping

Question 7

7. Why does capping occur in B-cells?

Answer 7

To fully process so it can phagocitize effeciently by moving to one area

Question 8

8. What specific T-cell releases Interleukin 2 to stimulate proliferation of an activated B-cell?

Answer 8

TH (Helper T-cells)

Question 9

9. What are Plasma cells and why are they produced?

Answer 9

Antibody/Immunoglobulin

Produced by B-cells called Plasma cells

Question 10

10. Do plasma cells ever leave the lymph node or just the antibodies that they produce?

Answer 10

Just the antibodies

Question 11

11. Describe the 4 mechanisms of Ab-Ag interaction: neutralization, agglutination, precipitation, opsonization.

Answer 11

Neutralization
Ab reacts with virus blocking its attachment to host cell
Ab reacts with toxins, blocking harmful effects

Agglutination
Ab reacts with whole bacteria cells and clumps them together
Opposes spread of pathogen
Enhances phagocytosis

Precipitation
Ab reacts with soluble Ag and converts it to a solid precipitate
Ag is inactivated and easily phagocytized

Opsonization
Abs promote phagocytosis of Ags with capsules
Abs bind to capsule then MØ binds to Ab enabling phagocytosis

Question 12

12. What are the 5 categories of Ab molecules?

Answer 12

IgM
IgG
IgA
IgE
IgD

Question 13

13. Which antibody is described as the “maternal Ab”?

Answer 13

IgG

Question 14

14. Which antibody is described as the “secretory Ab”?

Answer 14

IgA

Question 15

15. Which antibody is made first in response to a first encounter or primary response against an antigen?

Answer 15

IgM

Question 16

16. Which antibody is involved in the secondary response or memory response to an antigen?

Answer 16

IgG

Question 17

17. What is the difference between a primary response and secondary response to Ag?

Answer 17

Primary Response
1st exposure to Ag
Ab concentration short duration
IgM main Ab
7-10 days to initiate Abs

Secondary Response
2nd and any subsequent exposure to Ag
Ab concentration lasts longer
Stronger Ab response
IgG main Ab
Anamnestic (memory) response

Question 18

18. Which response to antigen is better and stronger: primary response or secondary response?

Answer 18

Secondary Response

Question 19

What are the 5 categories of Ab molecules and their functions? IgM

Answer 19

Involved with primary response against Ag
Largest Ab
5-10%

Question 20

What are the 5 categories of Ab molecules and their functions? IgG

Answer 20

Involved with secondary response against Ag
Memory Ab
“Maternal Ab” crosses placenta
80%

Question 21

What are the 5 categories of Ab molecules and their functions? IgA

Answer 21

“Secretory Ab”: tears, saliva, mother’s milk, mucous membranes
Provides protection in respiratory /gastrointestinal tracts
10%

Question 22

What are the 5 categories of Ab molecules and their functions? IgE

Answer 22

Major role in allergic response

0.5%

Question 23

What are the 5 categories of Ab molecules and their functions? IgD

Answer 23

Not clearly established – possibly involved with IgM
Perhaps helps in initial recognition of Ag
May be present on MØ surface to react with Ag
1-3%