B cells

Question 1

What is the antibody (immunoglobulin) structure made of?

Answer 1

4 polypeptide - two identical heavy chains (H) and two identical light chains (L) each containing a variable and constant region

Question 2

What is Fab?

Answer 2

fragment, antigen-binding region

Question 3

What is Fc?

Answer 3

fragment, crystalline

Question 4

What are the 5 isotypes of antibodies?

Answer 4

IgM, IgD, IgG, IgA, IgE

Question 5

What are the Fc receptors for IgG?

Answer 5

FcγR

Question 6

What are the Fc receptors for IgE?

Answer 6

FcεR

Question 7

What are the Fc receptors for IgA?

Answer 7

FcαR

Question 8

What are the Fc receptors for IgM?

Answer 8

FcμR

Question 9

What antibody class is predominant in blood?

Answer 9

IgG and IgM

Question 10

What are major antibodies in extracellular fluid?

Answer 10

IgG and IgA

Question 11

What antibody is usually predominant in secretions across epithelia?

Answer 11

IgA

Question 12

What antibody is usually provided to the foetus by the mother?

Answer 12

IgG

Question 13

What antibody is associated with mast cells just beneath epithelial surfaces?

Answer 13

IgE

Question 14

What is the function of IgA?

Answer 14

protect epithelial surfaces from infectious agents

Question 15

What do IgM and IgG activatye?

Answer 15

classical complement pathway

Question 16

What do Fcγ receptors facilitate?

Answer 16

phagocytosis of antibody-bound cells

Question 17

The main functions of all antibodies is?

Answer 17

1. neutralisation
2. opsonisation
3. antibody dependent cellular cytotoxicity (ADCC)
4. complement activation

Question 18

What makes up the B cell receptor (BCR)?

Answer 18

membrane bound immunoglobulin (IgM/IgD) with unique specificity
surface single antibody molecule (Igα or Igβ)

Question 19

What are the distinct roles in B cell activation?

Answer 19

performs first signal of activation - binding to cognate antigen
internalise antigen (APC function) to present MHC class II molecules

Question 20

What is an immunoreceptor tyrosine-based activation motif?

Answer 20

highly conserved region in the cytoplasmic domain
activated when receptors are ligated and produces an intracellular signal

Question 21

What are P nucleotides?

Answer 21

inserted nucleotides as a result of imprecise joining during V(D)J recombination

Question 22

What are N nucleotides?

Answer 22

are random nucleotides inserted at each VDJ joint by the enzyme terminal deoxynucleotidyl transferase (TdT)

Question 23

What increases diversity of B cell receptor?

Answer 23

N and P nucleotides

Question 24

What are the two types of B cell activation?

Answer 24

non protein antigens without T cell help
protein antigens require T cell help

Question 25

What antibodies are mostly produced by non protein antigen activating B cells?

Answer 25

IgM

Question 26

What antibodies are typically produced from protein antigens requiring T cell help?

Answer 26

antibodies with isotype switching and high affinity

Question 27

What are characteristics of T-independent B cell activation?

Answer 27

antigens are multivalent
response = fast
short-lived plasma cells

Question 28

What are characteristics of a T-dependent B cell activation?

Answer 28

antigen = protein component
two received signals
response = slower
memory B cells and long-lived plasma cells

Question 29

What are the two responses B cell receives during T-dependent activation?`

Answer 29

1. through antigen receptor
2. CD4+ T helper cell interaction (recognition of same antigens)

Question 29

What are the two responses B cell receives during T-dependent activation?`

Answer 29

1. through antigen receptor
2. CD4+ T helper cell interaction (recognition of same antigens)

Question 30

What can activated B cells act as?

Answer 30

professional APCs

Question 31

What is linked recognition?

Answer 31

see same parts of the same antigen
but B cells see it as naive
and T cells = “chopped up”

Question 32

What interaction is important between B cells and T cells?

Answer 32

CD40 and CD40 ligand on T cell

Question 33

What is affinity maturation?

Answer 33

process by which the affinity of antibodies produced in response to a protein antigen increases with prolonged or repeated exposure to that antigen

Question 34

What causes affinity maturation?

Answer 34

point mutations in V regions