Immune memory

Question 1

mechanisms of B cell memory recall

Answer 1

T dependent and T independent- T dependent is much more effective (CD4+ cell activation)

Question 2

where do T and B cells communicate?

Answer 2

germinal centres

Question 3

what activates naive T cells

Answer 3

CD28

Question 4

CD4+ recognise:

Answer 4

MHC II complexes

Question 5

CD8+ recognise:

Answer 5

MHC I peptides

Question 6

example of an immune regulation mechanism which occurs at the synapse

Answer 6

size-dependent segregation- more physical space between antibody and target means there is a less strong response

Question 7

examples of features which change depending on the state of an immune cell

Answer 7

cell surface molecules, division rates, TCR repertoires

Question 8

tuenover rates at each stage of T cell

Answer 8

slow in naive T cells- 50% of pop replenished in 9 months ish
activated- speedy, every 10-12 hours but can do up to every 6
intermediate for memory cells- half of pop in 15-70 days

Question 9

tradeoff in specificity of T cells

Answer 9

want to be somewhat specific as some antigens are more protective than others, but also can be good to have broad specificity to reduce escape risks

too many types- competition and ‘pushing out’ of some cells

more clones > better survival of responses, which is necessary for the response to be vaguely useful

Question 10

memory T cell sub-populations

Answer 10

effector- tissue and spleen migration routes
central- preferential migration through the lymph nodes

Question 11

CD4 vs CD8 memory

Answer 11

CD4- more diverse repertoire, gradual decline over time
CD8- large clone sizes, potentially more stable

Question 12

central vs effector memory

Answer 12

central lived longer, slower transition to function, more division before differentiation
>essentially, slower but larger effect

effector- short-lived, more rapid transition to function
>fast but smaller effect

Question 13

3 differentiation models

Answer 13

linear- naive > effector > differential division

bifurcative- asymmetrical cell division, differentiation from daughter cells

self-renewing- lymphoid cells move to non-lymphoid cells, rather than going through an intermediate

Question 14

are memory pools committed or non-committed?

Answer 14

some of both- there are biases in secondary responses, probably suggesting some level of commitment in memory cell pools