Lymphocyte regulation

Question 1

How can lymphocytes be regulated

Answer 1

tolerance - see it a lot so immune response decrease
removal of infectious agent - no signal for lymphocytes - apoptosis
Th release cytokines that stop it
T cell exhaustion

Question 2

What is tolerance

Answer 2

Tolerance limits response to persisting antigens (immunosuppressants/allergy immunotherapy) specific unresponsiveness to an antigen that is induced by exposure of lymphocytes to that antigen. Active
• Central tolerance – destroy T/B cells before enter circulation – b receptors edited and T cells may become regulatory
o If B cell recognise self – activate apoptosis of b cell in bone marrow
o T – bind MHC…
• Peripheral tolerance – in circulation

Question 3

What is the function of the autoimmune regulator (AIRE)

Answer 3

• Transcription factor – thymic expression of genes from peripheral tissues – self tolerance
• Mutations in AIRE – autoimmune polyendocrinopathy syndrome type 1
• Specific window of types of autoimmunity
• Good Ab against flu – immune response against virus, normally these T cells are destroyed because they’re similar to self antigens

Question 4

How does anergy affect regulation

Answer 4

less likely to be stimulated with co-stimulation if been exposed to antigen without costimulatory proteins previously. Need both MCH peptide combination and co-stimulatory factor

Question 5

What is ignorance

Answer 5

antigen level too low to be detected – immunologically privileged site. Risk of response is greater than that of infection/ compartmentalised from DC

Question 6

Antigen induced cell death

Answer 6

influenced by initial T cell activation events – induction of Fas ligand – CD8

Question 7

What is regulation

Answer 7

• T regulatory cells (Treg)
• Mutation in FoxP3 – IPEX (Immune dysregulation, Polyendocrinopathy, enteropathy, X-linked syndrome)
• Treg – CD4, FoxP3, high IL2 low IL7 receptors
• Secrete immune suppressive cytokines IL 10
• Natural – thymus (self recognition)
• Inducible – from mature CD4 – limit collateral damage

Question 8

When is regulation important

Answer 8

pregnancy - parasite

Question 9

Importance of regulation

Answer 9

avoid collateral damage
allergy - things not infections
autoimmune disease - attack own cells

Question 10

What is autoimmunity

Answer 10

• Immune response against self antigen
• Organ specific/systemic
• Susceptibility genes/env trigger
• Chronic and self-perpetuating
• Failure to get rid of self- reactive cells
• Inflammation
• Immune response against self/microbial antigens
• T cells and Ab
• RA IBD MS PSORIASIS

Question 11

What is allergy

Answer 11

• Response to non-infectious antigens
• IgE and mast cells – acute anaphylactic shock
• T cells – delayed type hypersensitivity

Question 12

what are hypercytokinema and sepsis

Answer 12

• Too much immune response
• Bacteria in blood stream/failure to regulate response
• Cytokine storm
• +ve feedback

Question 13

What is the cross regulation of cytokines

Answer 13

All have many effects on different cells
influence outcome
Focus immune response on 1 Th subset – one is dominant and shuts down the rest
The way T cells provide instructions for the rest of the immune system

Question 14

what is the function of IL-10

Answer 14

• Pleiotropic
• Downreg macrophages
• Antiinf
• Viral mimics – turn off immune system

Question 15

what is TB cell communication `

Answer 15

• T cell make CD40 ligand and B cell have receptor
• B licences T,. T licences B
• Cytokine from T changes the B cell output ie there is a different constant region - Ig class switch