B cells and antibody

Question 1

where do B cells develop

Answer 1

in the bone marrow

Question 2

what do B cells express

Answer 2

unique receptors
- B cell receptors
- secreted antibody

Question 3

what are plasma cells

Answer 3

activated B cells that secrete antibody

Question 4

what Immunoglobin mainly covers the B cell

Answer 4

IgM and IgD

Question 5

what does the BCR do

Answer 5

activate the B cell

Question 6

what anchors the BCR in the membrane

Answer 6

transmembrane domain (TM)

Question 7

what is the key difference between BCR and secreted antibody

Answer 7

secreted antibody lack a TM

Question 8

what are the 2 types of chains in the BCR and how many are there of each

Answer 8

2 heavy chains
2 light chains

Question 9

what are the 2 signals needed for B cell activation

Answer 9

1. the release of cytokines from CB4 cells
2. Binding of a native antigen

Question 10

what are the 3 functions of antibody

Answer 10

1. neutralization
2. opsonization
3. complement activation

Question 11

how does an antibody neutralize a cell

Answer 11

antibodies will stop the virus from infecting our host cells by blocking it from interacting with host cells

Question 12

how does an antibody carry out opsonisation

Answer 12

antibodies will coat the infected cells which will act as a signal for phagocytic cells to engulf the infected cell

Question 13

how does an antibody activate the complement

Answer 13

antibodies act as receptors for the complement proteins to bind - which leads to the formation of MAC
- MAC will then create pores in the cell

Question 14

what are native antigens

Answer 14

the antigen does not have to be processed to peptides (or in context of MHC)

Question 15

what is the antibody binding site called

Answer 15

epitope

Question 16

what type of molecules is IgG

Answer 16

monomer

Question 17

where are IgG distributed

Answer 17

• most abundant Ig class in blood
• very soluble in the blood

Question 18

what are the functions of IgG

Answer 18

1. Opsonization/Neutralizes - activated complement
2. only Ig class that crosses the placenta - provides passive immune system
3. targets virus/bacteria

Question 19

how is the half life for IgG molecules

Answer 19

around for weeks/months

Question 20

what type of molecule is IgA

Answer 20

dimer

Question 21

what 2 components does IgA have in its structure

Answer 21

J chain and secretory component

Question 22

how are IgA distributed

Answer 22

• present in secretions such as tears, saliva, mucus and breast milk
• monomeric in blood = meaning it is normally present as a monomer but forms dimers in secretions

Question 23

what are the functions of IgA

Answer 23

1. defense of mucus membranes - especially in the gut
2. present in breast milk
3. confers passive immunity on nursing infant
4. targets virus/bacteria

Question 24

what is the half life for IgA

Answer 24

relatively long life span of a couple of days

Question 25

what is passive immunity

Answer 25

babies get to develop immune response from mothers without having to encounter infection/virus/bacteria itself

Question 26

what type of molecules is IgM

Answer 26

pentamer

Question 27

what component does IgM contain

Answer 27

a J chain

Question 28

which Ig is the immune systems primary response

Answer 28

IgM

Question 29

where is IgM distributed

Answer 29

- Ig class produced after initial exposure to antigen - expressed on naive B cells

Question 30

what is the function of IgM

Answer 30

1. very effective in activating complement 2. targets extracellular bacteria 3. acts as antigen receptor (BCR)

Question 31

what type of molecule is IgE

Answer 31

monomer

Question 32

where is IgE distributed

Answer 32

present in blood in low concentrations

Question 33

what are the functions of IgE

Answer 33

1. immunity to multicellular parasites 2. allergic reactions

Question 34

what does IgE activate for parasite immunity and allergic responses

Answer 34

mast cells

Question 35

what type of molecule is IgD

Answer 35

monomer

Question 36

where are IgD distributed

Answer 36

expressed on naive B cells

Question 37

what are the functions of IgD

Answer 37

1. works together with IgM - acts as antigen receptor 2. main function is still unknown

Question 38

how common are IgD

Answer 38

rare

Question 39

what leads to the formation of plasma cells

Answer 39

stimulation of B cells by antigen and T cells

Question 40

how are memory B cells formed

Answer 40

a small number of stimulated B cells form a pool of memory B cells - generated through cell division

Question 41

what are the half lives of memory B cells

Answer 41

remains for years in blood or lymphatic tissue

Question 42

how are memory b cells and effector b cells different regarding BCR

Answer 42

memory b cells express antibody as BCR but does not secrete them

Question 43

how long does a primary immune response take to be activated

Answer 43

7-14 days before efficient antibody is produced to eliminate antibody

Question 44

what type of Ig is present in the primary immune response

Answer 44

mainly IgM

Question 45

what is the secondary immune response based of

Answer 45

the success of vaccination

Question 46

what does secondary immune response rely on

Answer 46

memory b cells

Question 47

how long does the secondary immune response take

Answer 47

fast = 2-3 days

Question 48

what antibody is produced in secondary immune response

Answer 48

mainly IgG with additional class switching to IgA and IgE

Question 49

what is the order of class switching for memory B cells

Answer 49

In memory B cells, the order of class switching (also known as isotype switching) generally progresses from IgM to IgG, followed by IgA and IgE.