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204 > The Adaptive Immune System 1 > Flashcards

The Adaptive Immune System 1 Flashcards

1
Q

B cell receptor is bound to which coreceptor?

A

CD19, igalpha and beta

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2
Q

Light chains are selective 2 types, which chromosomes?

A

Lambda
Kappa
Chromosome 2 and 22

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3
Q

How many variable segments in heavy and light chain?

A

H-65

L-70

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4
Q

How many diversity segments in heavy chain?

A

27

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5
Q

What do light chains not possess?

A

Diversity segments

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6
Q

How many possible combinations can be made in B cell?

A

100 trillion

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7
Q

What do alpha chains in T cells not possess?

A

Diversity segments, similar to light chain in B cell

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8
Q

How many possible combinations in T cell sequences?

A

Million trillion

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9
Q

Why are there more T cell sequences at VDJ than B cells?

A

T cells don’t undergo further hypersomatic mutation hence more are required

T cell pool fixed from puberty

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10
Q

Rearrangement of VDJ occurs at which sites?

A

Recombination signal sequences (RSS)
Contain: conserved segments of DNA composed of a hapatemer, spacer and a nonomer, 3’ of V segments and 5’ of J and both side of D segments

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11
Q

Rearrangements is catalysed by which 2 enzymes?

A

Recombination activating genes RAG 1 and 2

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12
Q

Steps in VDJ joining?

A

Cleavage
Repair/ diversity
Joining

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13
Q

Skid mice lack which enzyme?

A

DNA dependent protein kinases

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14
Q

Somatic hypermutation occurs where?

A

In a lymph organ

B cell encounters antigen, causing proliferation.

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15
Q

How does somatic hypermutation occur?

A

In the hyper variable region of light and heavy chains, point mutations that are adjusting the receptor

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16
Q

Are all affinities good?

A

After somatic hypermaturation, some have worse, better or same

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17
Q

What is mutation rate?

A

1 base per 1000, which is 1 million times higher mutation rate than observed in normal cell division

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18
Q

The billions of sequences that are not useful are where?

A

In introns

19
Q

Which enzyme drives somatic hypermutation?

A

Activation induced cytosine deaminase AID

20
Q

How does activation induced cytidine deaminase work?

A

Introduces uracil in the genetic code, which is spliced out and then replaced, usually a cytidine replacing

21
Q

What is affinity maturation?

A

Follicular dendritic cells present antigen to B cells than have undergone SHM.
Only those with high affinity

22
Q

In affinity maturation those B cells with low affinity will …?

A

Die, apoptosis

23
Q

What happens in class switch recombination?

A

Same receptor but different constant region

24
Q

IgA is adapted to penetrate?

A

Mucous membranes

25
Q

Why is class switch recombination needed?

A

Constant region can recruit different cell type to site

26
Q

How do you get igM and igD immunoglobulin?

A

In igD, the Mu segment is spliced off,

In igM, delta segment spliced off

27
Q

In CSR, which is the first targeted switch region?

A

S mu

28
Q

For CSR which enzyme is needed?

A

AID

29
Q

Which CSR occurs in B cells is determined by?

A

Follicular T helper cells

30
Q

For neutralisation and diffusion in extra vascular sites which immunoglobulin is needed?

A

IgG

31
Q

What is igD good at?

A

Sensitisation of basophils

32
Q

What is igE good at?

A

Sensitisation of mast cells

33
Q

What is igA good at?

A

Neutralisation and Transport across epithelium

34
Q

What is igM good at?

A

Activation of complement system

35
Q

Average life of B cells?

A

5 days

36
Q

Negative selection?

A

When receptors bind to self antigen too strongly then are deleted

37
Q

Examples of thymus dependent and independent antigens?

A

Dependent- requires T cells to induce antibody production e.g proteins

Independent e.g polysaccharides and lipids

38
Q

T cell independent responses only require which antibody?

A

IgM to detect simple repetitive antigens, modest affinity

No memory

B cells are activated by direct BCR crosslinking

39
Q

What is the signalling complex in the membrane for b and T cells?

A

Ig alpha and beta

T cells- CD3

40
Q

B and T cell interaction

A

MHC to TCR
CD80/CD86 to CD28 on T cells
T cell activation leads to up regulation of CD 40 L which bind to CD 40
Cytokine production from T cells 3rd signal

B cell proliferates and differentiates into antibody secreting B cell or becomes memory

41
Q

What does somatic hypermutation do?

A

Add point mutations

42
Q

The first switch region is always?

A

Su

43
Q

The second cut is determined by cytokines released by?

A

Follicular t helper cells

204 (58 decks)

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