"Microbiology/Immunology Immune Response" MARY

Question 1

What is the period of time called between when an antigen is introduced, and when antibody to that antigen can be detected?

Answer 1

Lag, inductive or latent phase

Question 2

Which response to antigen is faster in terms of making antibody, primary response or secondary response?

Answer 2

Secondary

Question 3

Name the critical differences between primary and secondary responses.

Answer 3

The secondary response displays:

1. shorter lag time
2. requires less antigen to induce a response
3. higher rates of antibody synthesis
4. higher peak of antibody titer possible
5. predominance of IgG
6. higher affinity of antibody for antigen
7. longer persistence of antibody

Question 4

What is an idiotype?

Answer 4

A variable region on surface antibody

Question 5

How many idiotypes can one B cell express?

Answer 5

One, that is why the full complement of B cells is necessary to respond to different antigens

Question 6

What is the “clonal expansion” of the responsive cells?

Answer 6

When a B cell proliferates, for example sometimes B cells can make up to 1000 daughter cells in as little as 10 days

Question 7

As the immune response continues, over time the antibodies being made express a higher affinity for the antigen. Why?

Answer 7

Selective expansion of successful clones

Question 8

The total population of B cells make up the ____ of antibody specificities.

Answer 8

repertoire

Question 9

What is the surface antigen on T-helper cells?

Answer 9

CD4

Question 10

T/F: T-cells recognize a different set of antigens than B-cells.

Answer 10

True, not only do they see antigens differently, they recognize different parts of an antigen.

Question 11

Most antigens that T-cells react to are:

Answer 11

proteins or peptides

Question 12

T-cells can activate B cells to do what?

Answer 12

Differentiate into plasma cells

Question 13

Factors produced by what cells are responsible for the shift from IgM to IgG?

Answer 13

T-cells

Question 14

If B-cells do not differentiate into plasma cells, what else can they become?

Answer 14

Memory cells

Question 15

How is antigen presented in a way that the T-cell will react to it?

Answer 15

The antigen can be on the surface of a presenting cell, or the antigen can be part of a co-stimulatory molecule like MHC.

Question 16

T/F: All immunogens require T-cell help to produce a response.

Answer 16

False. There are T-independent antigens, generally polymeric molecules having a large number of repeating units (ie mitogens) than can cause a cross-linking of the antibody on the B-cell. There are others, too, ie toll receptors etc.

Question 17

What is the basic function of antigen presenting cells (APCs)?

Answer 17

To initiate the interaction with antigen by endocytosis or phagocytosis.

Question 18

Lymphocytes respond to antigen that is presented with ____ MHC.

Answer 18

self

Question 19

What is the most important cell surface antigen?

Answer 19

CD28:B7. The T-cell has CD28 which binds to B7 antigen on the APC.
CD40L is also an important co-stimulatory signal on T-helper cells that binds to CD-40L on the B-cell.

Question 20

T/F: The presentation of antigen without co-stimulation between APC and lymphocyte does not induce immunity.

Answer 20

True

Question 21

What are the requirements of a “professional” APC?

Answer 21

1. Take up and process antigen
2. Have MHC-II on its surface
3. Present the antigen with the MHC-II antigen
4. Provide a co-stimulatory signal, ie B7.

Question 22

T/F: B-cells are capable of processing antigen, expressing MHC-II antigen and expressing co-stimulation.

Answer 22

True

Question 23

Give a few examples of the “best” APCs.

Answer 23

Dendritic cells

Langerhans cells