Immune Tolerance

Question 1

Consequences of excessive immune system?

Answer 1

Allergies. Autoimmune disease.

Question 2

Consequences of deficient immune system?

Answer 2

Infection. Cancer.

Question 3

Major allergy immune system cell?

Answer 3

Mast cell.

Question 4

What causes acute anaphylactic shock?

Answer 4

IgE and Mast cells.

Question 5

What causes delayed type hypersensitivity?

Answer 5

T cells.

Question 6

2 types of allergy?

Answer 6

Acute anaphylactic shock. Delayed type hypersensitivity.

Question 7

Types of failure of immune regulation?

Answer 7

Autoimmunity. Allergy. Hypercytokinemia and sepsis.

Question 8

What is Hypercytokinemia and sepsis?

Answer 8

Too much immune response.

Question 9

What do you call a t cell after it has binded to mhc complex on antigen presenting cell?

Answer 9

Effector.

Question 10

What converts a naive t cell to an effector t cell?

Answer 10

Antigen recognition. Co-stimulation. Cytokine release.

Question 11

What occurs as the pathogen is eliminated?

Answer 11

Apoptosis of lymphocytes that lose their survival signals (antigen). Formation of memory cells.

Question 12

What cells are involved in resolution and repair after infection is cleared?

Answer 12

Macrophages and fibroblasts.

Question 13

What are the two types of tolerance in immunity?

Answer 13

Central and peripheral tolerance.

Question 14

When does central tolerance occur?

Answer 14

Before immune cell enters bloodstream.

Question 15

When does peripheral tolerance occur?

Answer 15

Once immune cell is in bloodstream.

Question 16

What is central tolerance?

Answer 16

Lymphocytes that recognise self antigens are deleted (apoptosis) or made harmless before they enter bloodstream.

Question 17

What is peripheral tolerance?

Answer 17

Destroy or control any self reactive T or B cells which do enter the circulation.

Question 18

What can lead to apoptosis of t cell in thymus?

Answer 18

If the t cell doesn’t bind or binds too strongly to self mhc.

Question 19

What is negative selection in t cell central tolerance?

Answer 19

T cell binds to self mhc too strongly.

Question 20

What is positive selection in t cell central tolerance?

Answer 20

T cell binds to self mhc weakly.

Question 21

What is death by neglect in t cell central tolerance?

Answer 21

T cell doesn’t bind to self mhc.

Question 22

How can a T cell in the thymus encounter MHC bearing peptides in other parts of the body?

Answer 22

Autoimmune regulator gene (AIRE Gene).

Question 23

What is the Autoimmune regulator?

Answer 23

Transcription factor that expresses genes from other tissues. This allows T cells to test for self antigens.

Question 24

Mutations in autoimmune regulator gene causes what?

Answer 24

Multi organ auto immunity.

Question 25

What are the three pathways for naive b cells?

Answer 25

Plasma cells. Memory cells. Affinity maturation.

Question 26

Why is peripheral tolerance important in relation to b cells?

Answer 26

B cells undergo affinity maturation. B cells can turn from non self to self even after leaving maturation in bone marrow.

Question 27

What is anergy (deactivation of t cell)?

Answer 27

Type of peripheral tolerance. T cell binding to mhc but antigen presenting cell doesn’t have co stimulation proteins. Engagement of inhibitory receptors on T cell. T cell less likely to be stimulated in the future even if co stimulatory proteins are present.

Question 28

What is ignorance?

Answer 28

Type of peripheral tolerance. Antigen is present in too low of a concentration to trigger T cell response.

Question 29

What is antigen induced cell death?

Answer 29

Activation of t cell receptor leads to apoptosis. Binding of fas ligand to fas receptor causes apoptosis of t cell.

Question 30

What cytokines to T regulatory cells release?

Answer 30

TGF-Beta (
Transforming growth factor),IL-10,IL-35.

Question 31

How do Treg cells regulate immune response?

Answer 31

Inactivate dendritic cells so naive T cells aren’t activated. Inhibition of T cell effector functions.

Question 32

Treg CD phenotype?

Answer 32

CD4 and CD25 present.

Question 33

How do Treg cells regulate immune response if lymphocytes bind to self antigen?

Answer 33

T lymphocytes are activated by binding to self antigen on MHC in thymus or peripheral tissues. Activated lymphocytes release IL2. IL2 binds to IL2 receptor on Treg cells and foxp3 is expressed. Release of anti inflammatory cytokines such as IL-10. Inhibition of T cell activation or effector functions.

Question 34

Role of chemokines?

Answer 34

Cell migration.

Question 35

Role of cytokines?

Answer 35

Level of immune response. Cytokines shape transcription factor pathways. Transcription factor pathways result in different t helper cell types.

Question 36

What is foxp3?

Answer 36

Transcription factor that controls production of IL-10 in Treg cells.

Question 37

Mutation in foxp3 leads to?

Answer 37

IPEX syndrome.

Question 38

IL-10 function?

Answer 38

Anti-inflammatory cytokine. Blocks pro-inflammatory cytokines such as TNF, IL-6, IL-8 and IFN gamma. Downregulates macrophages.

Question 39

Natural regulatory t cells development?

Answer 39

Recognition of self antigen during maturation in thymus. Reside in peripheral tissues to prevent harmful reactions against self.

Question 40

Inducible regulatory T cells development?

Answer 40

Develop from mature CD4 T cells that are exposed to antigen in the periphery.

Question 41

How do T follicular cells activate B cell?

Answer 41

T follicular helper cell binds to MHC II peptide presented by B cell. Release of IL-21 from tfh activates B cell along with the costimulatory proteins.

Question 42

What can T helper cells do to B cells?

Answer 42

Drive immunoglobulin class switch.

Question 43

Complement protein c3b role?

Answer 43

Opsonisation.