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IMS Immunology > Lecture 45 - Tolerance > Flashcards

Lecture 45 - Tolerance Flashcards

1
Q

haematopoiesis

A

to make blood

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2
Q

positive lymphocyte selection

A

Need to recognise pathogenic antigens (non-self)

= bacteria, viruses…

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3
Q

negative lymphocyte selection

A

Need to ignore autologous (self) antigens to prevent auto-immune disease

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4
Q

tolerance lymphocyte selection

A

need to tolerate harmless non-self antigens to prevent damage/disease

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5
Q

Celiac disease = intolerance

A

damaged villi in the intestine due to gluten intolerance

leads to inflamed intestine and impaired food uptake

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6
Q

T cell maturation

A
  1. Lymphoid precurser cell in bone marrow matures to…
  • immature T cells = go to thymus = cortex
  • immature B cells = migrate to lymph nodes
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7
Q

immature T cells in cortex of thymus

A
  • proliferate and express both CD4 and CD8

- means can bind with both MHC I and II

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8
Q

positive selection = immature T cells in medulla, determines which co-stimulator remains on surface

A

encounter antigens presented by both MHC I and II, if they recognise any antigen = positively selected = survive

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9
Q

cytotoxic cell specialisation = medulla

A

cell recognised a peptide presented via MHC class I = keeps CD8+, loses CD4+ receptors

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10
Q

t helper cell specialisation = medulla

A

cell recognised a peptide presented via MHC class II = keeps CD4+ and loses CD8+ receptors

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11
Q

negative selection = middle of medulla of t cells

A

cells presented with self antigens = if the new T cells bind to any of these they get negatively selected = die

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12
Q

what percentage of T cells leave the thymus

A

5% = 2 million out of the 60 million that are produced in lifespan in cortex of thymus

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13
Q

non-self antigen presentation

A
  • macrophages
  • dendritic cells
  • cortical thymic epithelial cells (cortex
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14
Q

self antigen presentation

A
  • medullar thymic epithelial cells
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15
Q

medullar thymic epithelial cells

A

controlled by Aire gene = auto-immune regulatory gene,

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16
Q

Aire gene

A

mTECs = produce, breakdown and present proteins specific for cells in all organs of the body = self recognition by mature T cells outside of the thymus is prevented

17
Q

acquired tolerance = Eu-FEDS

A

Eutherian fetoembryonic defence system = foetal material (foetus, sperm, eggs, gametes) don’t express MHC molecules

18
Q

reproductive system acquired tolerance

A

cells = overproduction of glycoproteins = suppress immune system = because even if antigen presentation occurs, the lymphocyte activation is suppressed as the antigen cannot be reached

19
Q

t lymphocyte activation requires…

A
  • receptor-antigen recognition

- co-stimulation

20
Q

anergy

A

lack of co-stimulation means t cell won’t to antigen

21
Q

two regions on an anitbody

A

Fc and Fab

22
Q

Fc region on antibody

A

swappable region = class switching

23
Q

purpose of class switching

A

makes antibodies better suited for their location and function

24
Q

immature B cells produce mainly…

A

IgM (and some IgD)

25
Q

IgM

A

pentamer = low affinity = circulating first defence, binds many antigens to one antibody

26
Q

activated B cells…

A

switch Ig class depending on location and function = high affinity

27
Q

functions of the different immunoglobulins

A 
IgM = circulating first defense
IgE = histamine relesase mast cells = allergy
IgA = mucose, tears, saliva, breast milk
IgG = crosses placenta = foetus protection
28
Q

monoclonal antibodies

A

all have same target and same target sequence

29
Q

polyclonal antibodies

A

all have same target pathogen but not same target sequence, more than one activated b cell as antigen receptors recognise different antigens of the same pathogen

30
Q

somatic hypermutation

A

high rate of mutation, 1 in 1000, in VJD gene segments =

31
Q

benefit of somatic hypermutation

A

mature B cells continuously need to be activated in order to proliferate there will be a positive selection of the B cells with a higher receptor affinity for the pathogen

32
Q

when does somatic hypermutation occur

A

after first b cell activation in lymph node

33
Q

B cell maturation in lymph node

A
  • b cells mature in germinal centre of lymph node
  • divide and form clones
  • somatic hypermutation changed affinity
  • either positive or negative selection
34
Q

virus mutations

A
  • antigenic shift = genetic shuffling

- antigen drift = random mutations

IMS Immunology (4 decks)

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