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MICR221 > L16 B cells > Flashcards

L16 B cells Flashcards

1
Q

what are the precursors of B cells (2)

A

bone marrow stem cells

lymphoid precursors

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2
Q

where does maturation of B cells occur and how is it different to T cells

A

occurs in the bone marrow where T cells mature in the thymus

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3
Q

what can B cell turn into once activated

A

plasma cells

memory cells

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4
Q

what a memory cells

A

cell that hang around for a long period of time that can differentiate into plasma cells to secrete antibodies

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5
Q

what are plasma cells

A

antibody secreting cells

majority are short lived

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6
Q

where do some of the plasma cells end up if they arent short lived

A

bone marrow

thymus

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7
Q

example bacteria/toxin that if immunised the plasma cells will continue to produce antibodies in the bone marrow and thymus years later

A

tetanus toxin

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8
Q

how does communication between T cells and B cells occur

A

binding of MHC II to TCR

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9
Q

what can early B cells that haven’t turned into memory or plasma cells do

A

bind native (unprocessed) antigen to antibodies that are bound to the plasma membrane

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10
Q

what happens to B cells during an immune response

A

class switching

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11
Q

what is class switching

A

the constant region of the heavy chain of the antibody is changed (switched)

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12
Q

what does class switching do?

A

changed function of the antibody

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13
Q

What does IgA do

A

protect the mucoss

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14
Q

What is IgG

A

good all round antibody that can cross the placenta

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15
Q

what are antibodies composed of

A

two heavy chains and two light chains

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16
Q

how are the light and heavy chains of the antibodies attached

A

disulphide bonds

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17
Q

how are the two heavy chains attached

A

disulphide bonds

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18
Q

what is the last component of an antibody

A

glycoprotein (carbohydrate)

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19
Q

what does the carbohydrate on antibodies do ?

A

impart different functions

antigen recognition

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20
Q

two ways antibody can be expressed

A

membrane bound or secreted

21
Q

what determines if an antibody will be secreted or membrane bound

A

mRNA splicing
transmembrane domain that is present in naïve B cells undergoes splicing when it becomes a plasma cell so it will be secreted

22
Q

what types of B cell receptors complex (antibody + receptor complex) do naïve B cell express on their surface

A

IgM and IgD

23
Q

what molecules do IgM and IgD associate with

A

Ig-alpha

Ig-Beta

23
Q

what molecules do IgM and IgD associate with

A

Ig-alpha

Ig-Beta

24
Q

What are Ig-alpha and beta

A

signalling molecules

transmembrane proteins

25
Q

what do the signalling molecules do?

A

signals the B cell to activate

26
Q

where does isotype switching of the B cells occur during an immune response

A

thymus

27
Q

what happens during the generation of diversity

A

B cells are rearranging their BCR

28
Q

are any B cells the same

A

no

29
Q

components of the light chain of a B cells

A

V
J
C

30
Q

what happens to the V and J regions during DNA rearrangement

A

1 V and 1 J gene are spliced together

31
Q

what happens to any genes between the V and J genes that are being combined

A

from a circle and float away to be degraded

32
Q

how many genes are in the V regions

A

50

33
Q

How many genes are in the J region

A

5

34
Q

How many genes are in the D region

A

25

35
Q

what is the C region/ what does it do

A

constant region
complement activation
binding to phagocytes through FC receptor

36
Q

can the C region change?

A

yes, class switching can occur but not during gene rearrangement

37
Q

how are B cells activated

A

recognise native antigen

receive help from CD4 T cell

38
Q

what happens to the native antigen when it binds to a B cell antibody

A

digested into peptides in an endosome and presented on MHC II to T cell

39
Q

what is the key difference between plasma cells and B cells

A

extensive ER and golgi for producing large amounts of antibodies

40
Q

what happens to a memory cells that comes into contact with antigen

A

becomes a plasma cell

does not require a T cell

41
Q

what is the type of antibody isotypes that is the first burst during a primary immune response

A

IgM

42
Q

during a secondary or further immune response what are the memory cells inclined to do

A

class switch to IgG

43
Q

where and how often does class switching occur

A

heavy chain

constantly

44
Q

what is IgE function

A

parasites and allergic respeonses

45
Q

what is IgA function

A

mucosal protection

46
Q

how does class switching occur

A

the M and D regions of the coding chain are ‘looped out’

47
Q

what happens to a B cell that is autoreactive to self antigen

A

programmed to die

apoptosis

MICR221 (23 decks)

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