Antibody, lymphocytes, generation of diversity

Question 1

How do T cell and B cell receptors differ

Answer 1

T cell receptor-heterodimer (2 chains are different to each other), consists of alpha and beta chain and there is 1 binding site
B cell receptor-2 identical heavy and light chains and 2 antigen binding sites

Question 2

What are the properties for memory in the adaptive immune system

Answer 2

same principle for B and T cells. Higher frequency of specific cells, respond more rapidly. Only in adaptive immunity

Question 3

How long does adaptive immunity take for first exposurre and booster expossure

Answer 3

1st-12 days

Booster-5-7 days

Question 4

In B cells, how does the gene rearrangement of the antibody work

Answer 4

Heavy chain comprised of 48 V, 27 D, 6 J=7776 combinations of VDJ
Light chain-consists of V and J, 340 alternatives
So 7776x340=2643840 combinational diversity
Junctional diversity also arises because joining is not precise and nucleotides are added and removed from junctions including rearrangement

Question 5

Where does development with gene rearrangement of B and T cells happen

Answer 5

B cell=bone marrow

T cell=thymus

Question 6

What does binding of B cell receptors result in

Answer 6

secretion of antibodies which have the same specificity as expressed by the B cells

Question 7

What do the variable and constant regions of anrtibody determine

Answer 7

Variable=determines specificity (kappa/lambda)
Constant region of heavy chain=determines isotype/classes of antibodies (IgM, IgG, IgE etc.). This can be further split into subclasses which are coded by different constant region gene segments (IgG1, IgG2 etc.)

Question 8

Label the heavy+light chains, constant+variable regions of antibody

Answer 8

ref. notes

Question 9

What kind of mechanisms are used for binding of antigen to antibodies in the variable region

Answer 9

lock and key, electrostatic charge, attraction of opposite charge

Question 10

What are the functions of antibodies

Answer 10

Neutralise toxins and viruses by binding to them and blocking their interaction with other cells
Opsonise pathogens by binding to them to promote phagocytosis and killing activity by other cells by recognition of Fc receptors
Activate the complement cascade which helps kill pathogens
agglutinates particles

Question 11

Where is IgG found, what is it used for and what does it do

Answer 11

serum
measurement of antibody titre in response to vaccine
IgG is good at opsonisation. Coating pathogens so phagocytic cells can recognise them. Pathogens coated in IgG become targets for killing by NK ccells (aantibody dependent cellular cytotoxicity)

Question 12

What are the 4 subclaasses of IgG and what is it named according to

Answer 12

IgG1, IgG2, IgG3, IgG4 named by increasing concentration in serum

Question 13

IgA

Answer 13

monomer-found in serum

Dimer-2 monomers joined by joining J chain (specific function on mucosal surface), has 4 binding sites

Question 14

IgM

Answer 14

first antibody made in immune response, pentameric (5 units joined), 10 possible binding sites (high avidity=ability for whole molecule to bind rather than 1 particular binding site), agglutination

Question 15

IgE

Answer 15

mast cells have receptors for IgE
Individuals with allergy have higher conc in serum. Pollen fom cross links because IgE cause mast cell degranulation, granules released and symptoms of allergies given

Question 16

Which antibodies with the same specificity are expressed on the surface of newly formed B cells

Answer 16

IgM and IgD

Question 17

Affinity maturation how it happens

Answer 17

B cell+specific antigen+help from T cells->enter germinal centre for dividing B cells–>B cell divide rapidly ->mutate immunoglobulin variable region gene by somatic hypermutation->high affinity variants are selected in germinal centre. B cells can also class switch so it can express isotypes other than IgM and IgD

Question 18

What are the 2 populations of cells leaving the germinal centre

Answer 18

quiescent circulating memory B cells: locate to BM or intestine
Affinity matured, possibly class switched: bone marrow plasma cells can secrete protective antibodies for a lifetime.

Question 19

How does the antibody response change from primary and secondary response

Answer 19

IgG rises higher because precursor frequency is higher. Titre higher due to high affinity

Question 20

What are monoclonal antibodies used for

Answer 20

treating autoimmune disase like rheumatoid and inflammatory disease like Crohn’s as well as cancer

Question 21

What are monoclonal antibodies

Answer 21

Memory B cell clones, individual cells comprising the memory clones will most likely be different due to somatic hypermutation

Question 22

What is a chimeric antibody

Answer 22

Mouse monoclonal is engineered so that the mouse variable regions of heavy and light chains are associated with human constant regions. Have ending –ximaab

Question 23

What happens when monoclonal antibodies are humanissed

Answer 23

only parts of the variable region that contact antigen are from the mouse
Ends with -zumab

Question 24

Fully human monoclonal antibodies

Answer 24

ending -umab

Question 25

Red blood cell antigens, what antibodies, red cells reactive with, plamsa reactive with

Answer 25

ref. notes

Question 26

How can cross placental transfer of IgG targeting rhesus antigen from mother to foetus cause issue

Answer 26

Mother who is Rh- has IgG antibodies to Rh following exposure to Rh antigen from first pregnancy->child was Rh+ causing haemolytic disease and RBC lysis.
Treatment: plasmapheresiss. IgG antibodies removed from system of baby and baby can create its own RBC

Question 27

What has Fc receptors

Answer 27

Phagocytes+macrophage

Question 28

In T cell receptors, how does gene rearrangement work

Answer 28

In alpha chain-50 v and 50j and 1 alpha constant region
In beta chain-50 v, 2 d, 13 j and 2 constant regions
Any alpha chain can combine with any beta chain