Immunotolerance

Question 1

Tolerance is associated with the lack of response to a -?

Answer 1

Specific, self-antigen

Question 2

What is implied with central and peripheral tolerance of T cells?

Answer 2

• Central​
  
  • Negative Selection: Reaction to self antigens
  • Positive Selection: Reaction to self MHCs
    
    • CD4/ CD8 Commitment
• Peripheral
  
  • Lack of co-stimulation = anergy
  • Treg cells remove/ block B7 receptors on APC’s preventing T cell activation
  • Treg cells increase IL-2R’s for more uptake and produce TGF beta and IL-10

Question 3

What is implied with central and peripheral B cell tolerance?

Answer 3

• Central
  
  • ​Receptor editing with reactivation of RAG genes to change antigen specificity and Ig light chain
  • Deletion/ apoptosis
  • Anergy/ unresponsiveness
• Peripheral
  
  • ​Lack of co-stimulation leads to anergy
  • Deletion/ apoptosis
  • CD32b (Fc gamma RIIb), an inhibitory receptor on B cells to trigger apoptosis

Question 4

How long can both T and B cells be made tolerant?

Answer 4

T cells: 24 hours

B cells: 10 days

Question 5

How long can both T and B cells remain tolerant?

Answer 5

T cells: 100 days

B cells: 50 days

Question 6

If a T cell has an increased presence of occupied or saturated T cell receptors from an antigen, what will occur?

Answer 6

Apoptosis

Question 7

If a T cell has a low level of its receptors occupied or saturated by antigens, what will occur?

Answer 7

Thymocyte proliferation

Question 8

Describe the avidity model, in relation to very low, intermediate/ low, and high avidity interactions.

Answer 8

Very low: death by neglect

Low/ intermediate: positive selection for thymocytes

High: clonal deletion

Question 9

Very high doses of an antigen can induce -?

Answer 9

Immune paralysis, as increased concentrations of circulating antigens will bypass APC’s and interact directly with T helper cell receptors without co-stimulation (leading to anergy)

Question 10

True or False: The adaptive immune responses are antigen driven, so in cases of increased antigen concentrations, there will be a prolonged immune response.

Answer 10

True

Question 11

What do IgG and IgM suppress?

Answer 11

IgG: Both IgG and IgM

IgM: Only IgM

Question 12

While CD4+, CD25+, and CTLA-4 are present as receptors of these cells, what transcription factor is essential for the production of cytokines for suppression of T cells and macrophages?

Answer 12

Fox3P+

These are T reg cells

Question 13

As an immunoregulatory cytokine, what immune response(s) is inhibited by IL-10?

Answer 13

Both the innate and adaptive immune responses

Question 14

True or False: Self-reactive B cells can still develop, as a result of somatic mutations, in secondary lymphoid organs.

Answer 14

True