Immune Response

Question 1

What are the stages of the immune response?

Answer 1

lag/inductive/latent phase- time after primary exposure before Ab can be detected
Log/exponential phase- Ab production and rate of production increases
steady state- peak Ab concentration reached
decay/decline- decline followed by period when small amount of Ab can be detected

Question 2

How is secondary response improved from primary? (7)

Answer 2

shorter lag time, higher rates of Ab synthesis, higher peak of Ab titer, longer persistence of Ab, IgG, higher affinity of Ab, requires less Ag

Question 3

What is an idiotype?

Answer 3

single variable region expressed by a B cell

Question 4

What do the total population of B cells make up?

Answer 4

the repertoire of Ab specificities

Question 5

What is clonal expansion? What is the advantage to it?

Answer 5

• B cell proliferation stimulated by T helper cells in response to specific Ag
• results in increased affinity over time of the response because as the Ag concentration goes down only the higher affinity Abs can bind it and so only their B cells are stimulated to continue production

Question 6

What is a hapten?

Answer 6

small molecule that can’t induce its own Ab response on its own, but can when bound to carrier protein
-T cells recognize the carrier protein and Ab response is against either the carrier or hapten

Question 7

How do T helper cells affect B cells?

Answer 7

stimulate differentiation into plasma cells or memory cells and class switch fro IgM to IgG

Question 8

What is a T-independent Ag?

Answer 8

polymeric molecule with large number of repeating subunits that can crosslink Ig on a B cell, polyclonal activatiors of Bcells that provide mitogenic signal to B cell that would have been provided by T cells
-thought to act through Toll-like receptors

Question 9

How do you enhance APC phagocytosis?

Answer 9

interaction with complement (C3b-receptor mediated), antibody, or specific receptors that recognize pathogen

Question 10

To be a professional APC, what four things do you need:

Answer 10

1. take up and process Ag
2. MHC class II on surface
3. present Ag with the MHC class II
4. provide costimulatory signal (B7)

Question 11

What happens to T cells that receive only specific signal without costimulatory signal?

Answer 11

become anergic

Question 12

What happens to T cells that receive only co-stimulatory signal and no specific signal?

Answer 12

no effect

Question 13

Where is the memory in the immune response?

Answer 13

B cells that make IgG and T helper cells that stimulate B cells

Question 14

If you immunize with Acarrierprotein-hapten, you get a primary response. If the second time, you use Bcarrierprotein-hapten, do you get a secondary repsonse?

Answer 14

No, T cell doesn’t recognize the carrier even though B cell response is the same to the hapten. Only if both cells react do we get a good immune response.

Question 15

How do adjuvants improve immune response?

Answer 15

• stimulate T cells by better stimulating phagocytosis by APC to present to T cells
• may cause precipitation of Ag out so it can be phagocytosed more rapidly to present to T cells

Question 16

Which cells act as APC first in the immune response? later?

Answer 16

first, professional APC such as dendritic cells, macrophages, etc
later, B cells present Ag to T cells