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MEDSCI 202 > Lecture 19 > Flashcards

Lecture 19 Flashcards

1
Q

where does central tolerance occur

A

primary lymphoid tissue

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2
Q

what does central tolerance do

A

eliminate clones that recognise self

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3
Q

what are the 3 mechanisms for lymphocytes that recognise self

A

apoptosis, helper cells become Treg cells and B cells may ingest their receptor and undergo receptor editing

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4
Q

what are T cell populations based on

A

1) TCR has right sequence and shape so it can bind MHC
2) Can recognise a foreign peptide in grove of MHC and not self peptide

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5
Q

what happens to majority of thymocytes

A

80% die via neglect as most thymocytes that dont bind self dont get provided a signal during maturation

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6
Q

what happens to the thymocytes that bind strongly to self

A

20% of T cells die via apoptosis as they bind too strongly

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7
Q

where do Treg cells come from

A

small amount of thymocytes that bind strongly to self peptide turn into Treg cells

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8
Q

what thymocytes are positively selected

A

the 1-2% of thymocytes that dont react with self peptides

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9
Q

how are Treg cells formed

A

small subset of negatively selected are presented with a self peptide however they dont receive signals to die

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10
Q

What do Treg cells do

A

provide peripheral tolerance mechanisms and if deleted provides autoimmunity

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11
Q

what are the mechanisms for periphreal tolerance

A

Normal T cell response, Anergy, Suppression, Deletion, Ignorance

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12
Q

what is normal T cell response

A

produces effector and memory T cells

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13
Q

what is suppression

A

when there is a block in activation so Tregs control self reactive cells

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14
Q

what is deletion

A

apoptosis

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15
Q

what is anergy

A

functional unresponsiveness

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16
Q

Where does central tolerance in B cells occur

A

Bone marrow

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17
Q

what happens if they dont receive signals

A

die via apoptosis

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18
Q

What are B cells able to do if they bind self

A

B cells can ingest their receptor and edit it. It is then redisplayed as a different receptor.

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19
Q

what happens if the B cells arent able to edit their receptor

A

it dies via apoptosis

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20
Q

What happens if the B cell escapes out into the periphery

A

it becomes anergic (unresponsive) due to its low binding affinity

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21
Q

what is periphreal tolerance

A

a back up mechanism that silences any lymphocytes that recognise self

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22
Q

what is clonal anergy

A

self reactive lymphocytes that are not activated properly and become resistant to stimulation

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23
Q

what does T cell tolerance lead to

A

B cell tolerance

24
Q

what is the breakdown of tolerance

A

failure of an organism to recognize its own parts as self due to loss of tolerance

25
Q

what are the 4 mechanisms for the breakdown of tolerance

A

genetic suceptibility, infections, influx of self reactive lymphocytes and activation of self reactive lymphocytes

26
Q

what are susceptibility genes

A

1) complement genes are impared immune complex clearance
2) immunogoblin and TCR are antigen receptor genes
3) cytokines and co stimulators are regulatory genes
4) antigen presenting enes are class 1 and class 2

27
Q

what is sympathetic ophthalmia

A

damage to eye after trauma which results in the release of intracellular antigens which active T cells in both eyes

28
Q

what is molecular mimicry

A

body generates lymphocytes that display bacterial pathogen

29
Q

what are 2 examples of molecular mimicry

A

acute rheumatic fever and multiple sclerosis

30
Q

what is acute rheumatic fever

A

group A streptococcus post infection complication

31
Q

what is multiple sclerosis

A

affects brain and spinal cord

32
Q

how does multiple scierosis work

A

autoimmune attack against myelin sheat that sorrounds nerve fibres of brain and spine. the immune response causes gradual destruction of myelin and damage to nerve axons

33
Q

what are the symptoms of multiple scierosis

A

change in sensation, visual problems, muscle paralysis

34
Q

how does acute rheumatic fever work

A

M protein in cell wall protein shares epitopes with proeins in heart mucles and valve

35
Q

how do you prevent acute rheumatic fever

A

long term dose of antibiotics

36
Q

what is type 1 diabetes

A

immune system attacks beta islets cells of pancreas

37
Q

what effect does type 1 diabetes have of Treg cells

A

normal levels of Treg cells with decreased function

38
Q

how do you combat type 1 diabetes

A

daily injections of insulin

39
Q

what is rheumatoid arthritis

A

autoimmune attack on synovial tissue and cartilage in joints

40
Q

what are the symptoms of rheumatoid arthritis

A

ligament, tendon and bone degradation with pain

41
Q

what effect does rheumatoid arthritis have on Treg cells

A

increased levels of Tregs with decreased function

42
Q

what is a distinctive feature of rheumatoid arthritis

A

presence of rheumatoid factor in patient serum

43
Q

what is rheumatoid factor

A

autoantibodies that bind to own IgG

44
Q

what is coeliac disease

A

abnormal reaction to gliadin

45
Q

what is gliadin

A

gluten protein found in wheat

46
Q

how does coeliac disease work

A

inflammatory reaction flattens villi of intestine which interferes with nutrient absorbtion and frequently leads to anemia

47
Q

how do you combat coeliac disease

A

removal of gluten from diet

48
Q

3 ways to treat autoimmune disease

A

replacement, infection treatment, remove trigger

49
Q

what is biologics

A

more targeted approach to suppress the immune system

50
Q

what is biologics used for

A

rheumatoid arthritis

51
Q

what is NSAIDs and what does it do

A

non steroidal anti inflammatory drug which blocks symptoms like pain or swelling

52
Q

what is DMARDs and what does it do

A

disease modifying anti-rheumatic drugs which are slow acting immune suppressants

53
Q

what are examples of corticosteroids

A

NSAIDs and DMARDs

54
Q

what do corticosteroids do

A

reduce inflammation

55
Q

what does removing the trigger work on

A

coeliac disease by removing gluten from the diet

56
Q

what is an example of infection treatment

A

penicillin injects for rheumatic fever

57
Q

what is an example of replacement treatment

A

replace lost secretions or inhibit endocrine function such as type 1 diabetes with their insulin injections

MEDSCI 202 (6 decks)

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