Adaptive Immunity II

Question 1

Where does antigen recognition by a naive T cell take place?

Answer 1

In secondary lymphoid organs following antigen presentation

Question 2

What drives the activation of antigen-specific T cells and the clonal expansion of the population?

Answer 2

the autocrine and paracrine action of IL-2

Question 3

Where do memory or infected cells go after they leave the lymphoid organ?

Answer 3

They migrate to the infected tissue
Once the antigen/pathogen has been cleared the cells will then die via apoptosis

Question 4

What are the three signals required for optimal T-Cell activation and proliferation?

Answer 4

• Signal 1= antigen-specific TCR engagement (MHC I and MHC II)
• Signal 2= contact with co-stimulatory ligands
• Signal 3= cytokines directing T-cell differentiation into distinct effector cell types

Question 5

What is the co-stimulatory receptor that helps to facilitate activation?

Answer 5

CD28

Question 6

What is the negative co-stimulatory receptor that helps to turn the activation off?

Answer 6

CTLA-4 (CD152)

Question 7

How does CTLA-4 (CD152) work?

Answer 7

It is induced within 24 hours after activation (peaks 2-3 days post stimulation)

Question 8

What are the 5 distinct subset pathways T cells can enter after activation?

Answer 8

• TH1 and TH2
• TH17
• TREG
• TFH

Question 9

What are the two things that signals 1 and 2 induce in T cells?

Answer 9

• Up-Regulation of Pro-Survival genes
• Transcription of IL-2 AND IL-2R genes

Question 10

What is the difference between central memory cells and effector memory cells?

Answer 10

Central Memory Cells
* reside in/travel between secondary lymphoid tissues
* Live longer/divide more times than TEM cells
* Are rapidly reactivated by second Ag exposure
* Can differentiate into several subset types depending on cytokine environment

Effector Memory Cells
* Travel to/between tertiary tissues
* Contribute better to first-line defenses
* Rapidly re-acquire effector functions on second Ag exposure

Question 11

What are the two B cell responses elicited by distinct antigen types?

Answer 11

• T-Cell dependent response
• T-Cell independent response

Question 12

When are T-Cell dependent responses usually generated?

Answer 12

Upon recognition of the protein Ag

Question 13

When are T-Cell independent responses usually generated?

Answer 13

Upon exposure to multivalent/ polymerised Ag

Question 14

What is somatic hypermutation?

Answer 14

somatic hypermutation is a process that introduces random mutations into the variable regions of the immunoglobulin genes
(the genes that encode B Cell antibodies)
- occurs in the germinal centres

Question 15

What is Class Switching?

Answer 15

Class switching is a process that occurs in mature B cells, where the constant region (or isotype) of the antibody molecule is changed without altering the specificity for the antigen.

Question 16

What are some of the ways antibodies can mediate the clearance and destruction of a pathogen?

Answer 16

1. Virus and Toxin neutralisation
2. Opsonisation
3. Complement fixation and formation of the membrane attack complex
4. Antibody-Dependent Cell-Mediated Cytotoxicity

Question 17

What are the five major classes of secreted antibodies?

Answer 17

1. igG
2. igD
3. IgE
4. igA (dimer)
5. igM (pentamer)

Question 18

What can occur during somatic hypermutation?

Answer 18

• Mutations can increase over time
• Higher-affinity B cells may actually steal Ag from lower-affinity B cells, promoting their own survival signals

Question 19

What are the most common surface markers in cloven-hoofed animals

Answer 19

gamme delta T cells

Question 20

In what animals are offspring totally reliant on receiving antibodies from their parents due to the chorionic epithelium being completely in contact with the uterine tissues

Answer 20

Ruminants, Pigs and Horses