L3. Recognition of antigen

Question 1

where do b cells and t cells differentiate

Answer 1

both originate in bone marrow
- B cells diff in bone marrow
- T cells diff in thymus

Question 2

what are BCRs and TCRs

Answer 2

the receptors on surface - recognise foreign moelcules

Question 3

2 main functions of antibodies

Answer 3

bind foregin antigens
mediate effector functions to neurtralise/eliminate foreign invaders

Question 4

what enzyme can cleave the disulphide bond linking the heavy chains

Answer 4

papain

Question 5

Fab

Answer 5

Fragment antigen binding

Question 6

Fc

Answer 6

fragment crystalizable

Question 7

what does hinge region allow for

Answer 7

slight shape change

Question 8

what does the antibody recognise

Answer 8

antigenic epitope

Question 9

what is hypervariable region on antibody also known as

Answer 9

complementary determining region

Question 10

2 types of epitopes

Answer 10

linear and conformational
conformational more commone

Question 11

what type of forces involved in antigen antibody binding

Answer 11

non-covalent

Question 12

affinity def

Answer 12

strength of bidning between epitope and antibody antigen binding site

Question 13

avidity def

Answer 13

overall stergnth of antibody antigen complex eg if its using both bidning sites

Question 14

Fc portion of antibody

Answer 14

Fc portions is responsible for its biological activity
e.g. the effector stuff

Question 15

4 main effector functions of ABs

Answer 15

neutralisation
opsonisation
activation of complement
ADCCn

Question 16

neutralisation

Answer 16

• antibodies prevent pathogen from binding target
• important in viruses: prevents them getting into cell
• many vaccines elicit this response

Question 17

opsonisation

Answer 17

ABs target the pathogen for phagocytosis
- Fc domain on AB binds to Fc receptor on antigen

Question 18

Complement activation

Answer 18

the AB activates the complement system:
- formation of pores in bacterium
- or induce phagocytosis again

Question 19

ADCC

Answer 19

Antibody dependent cell mediated cytotoxicity

• so cells express viral proteins in membrane after being infected, and ABs bind to this
• mediates extracellular killing of the cell

Question 20

what Fc receptor is on NK cells

Answer 20

FcyRIIIa

Question 21

what do antibody classes depend on

Answer 21

C region used by heavy chain

Question 22

diff antibody classes

Answer 22

IgG
IgM
IgD
IgA1
IgE

Question 23

IgG

Answer 23

most abundant
4 types
IgG1 most common

Question 24

IgM

Answer 24

earliest antibody made after Ag contact
pentamer
up to 10 bidning sites

Question 25

IgD

Answer 25

rare, function unclear

Question 26

IgA1

Answer 26

mainly in mucosa
2 types

Question 27

IgE

Answer 27

lowest in serum
produced by mast cells
allergy and worms

Question 28

what is J chain

Answer 28

allows IgM and IgA to form polymers, bigger strcutres of ABs

Question 29

what is a major site of B cell activity and antibody production

Answer 29

Mucosal Associated Lymphoid Tissue (e.g. gut)

Question 30

what antibody usually associated with MALT

Answer 30

IgA
5g/day

Question 31

where is IgA predominant in

Answer 31

external secretions
saliva, tears, mucus
(in dimer form)