Antibodies, Antibody Diversity and T-cell development - Powell

Question 1

What is an antigen?

Answer 1

Anything that can be specifically bound by cells of the adaptive immune system (B or T cells).

Question 2

Which cells bind in a specific manner to antigen (Ag)?

Answer 2

The lymphocytes

• T cells (cell meditation immunity)
• B cells (Humoral immunity)

Question 3

What is an antibody?

Answer 3

Also known as an immunoglobin it is a membrane bound B cell receptor.

Question 4

What are the primary functions of antibodies?

Answer 4

1. antigen binding and recognition
   - Bind ALONE may neutralize antigen.
2. Trigger the elimination of foreign Antigen.
   - Direct antigen neutralization
   - opsonization
   - activation of the complement cascade

Question 5

Where are B cells and T Cells generated?

Answer 5

Both begin in the bone marrow

Question 6

What is a hyper-variable region?

Answer 6

Where antigens bind.

Question 7

Where do T cells mature?

Answer 7

the Thymus

• Postive selection = cortical region
• negative selection = Medullary region

Question 8

Where do T cells mature?

Answer 8

In the cortical region of the Thymus

Question 9

Where do T cells mature?

Answer 9

In the Thymus

Question 10

To what does FcR Bind?

Answer 10

Binds to Fc region on antibody

Question 11

What is the end result of FcR Binding?

Answer 11

Keeps pathogen close, allowing effector cell to preform opsonization on pathogen.

Question 12

Describe positive and negative selection of T cells and where it occurs…

Answer 12

Cells are either kept or deleted based on how they interact with antigens (IE they are removed if they don’t play nice with self antigen.)

Positive selection = kept b/c of low avidity interaction with self antigens.
Negative selection = deletion if cell responds with high avidity with self antigens.

Question 13

How is antibody diversity achieved?

Answer 13

Because of the human heavy chain variable region. This is possible due to VDJ gene segments. (variable, Diversity & joining)

Question 14

What is hematopoiesis?

Answer 14

Production of RBC

Question 15

Where do B cells mature?

Answer 15

In the bone marrow

Question 16

What are the components of Antibodies?

Answer 16

Two fragments

• Fab = antigen binding (light chains only found here)
• Fc = crystallizable fragment

4 Chain structure

• 2 identical heavy chains that spans Fab and Fc
• 2 identical light chains = only Fab

Question 17

Classes of immuoglobins are defined by what?

Answer 17

Heavy chain differences.

Question 18

Where are IgA’s found?

Answer 18

Mucosal areas, saliva and breast milk

Question 19

Where are IgD’s found?

Answer 19

Functions mainly as antigen receptor on B cells that have not been exposed to antigens.

Question 20

What do IgE’s do?

Answer 20

Binds to allergens and trigger histamine release from mast cells and basophils.

Question 21

What does IgG do?

Answer 21

4 forms: provides majority of antibody based immunity adjacent invading pathogens. *Only antibody capable of passing over placenta to give passive immunity to fetus.

Question 22

What is Combinatorial diversity?

Answer 22

Is the creation of antibody diversity in the Ig repertoire through the joining of various gene segments.

Question 23

What is a naive B Cell?

Answer 23

One that has never seen its antigen before

Question 24

The ability of a cell to undergo class switching allows what?

Answer 24

Allows for the generation of multiple antibody isotopes with the same antigen specificity.

Question 25

Where does IgM reside?

Answer 25

On naive B cells

Question 26

Do T cells undergo class switching?

Answer 26

No! only B cells (Plasma cells)

Question 27

Do T cells undergo class switching?

Answer 27

No! only B cells!

Question 28

The Lymphocytes that do not bind do MHC through their TCR are destine for what?

Answer 28

destine to die via apoptosis

Question 29

The BCR on Naive B cell can only be ____ OR ______.

Answer 29

IgM or IgD