Lecture 5- Immune mechanisms: adaptive immunity

Question 1

examples of adaptive receptors which antigens can respond to

Answer 1

antibodies, B cell and T cell receptors

Question 2

lymphocyte division rates

Answer 2

about once every 12 hours (can be maintained for weeks), once per 6h at the absolute most

Question 3

differences between primary and secondary infection wrt adaptive response

Answer 3

primary- much slower for adaptive processes to kick in (week/2)
secondary- quicker, takes 2-4 days for a peak response

Question 4

what is an antibody

Answer 4

soluble form of the B cell receptor

Question 5

how are TCRs formed

Answer 5

rearrangement of genomic segments, e.g. through recombination

Question 6

term for the large amount of receptors generated

Answer 6

anticipatory repertoire

Question 7

how does receptor selection occur

Answer 7

clonal distribution of receptors, testing for inappropriate activation, killing off of these ‘inappropriate’ cells

Question 8

how do T cells develop

Answer 8

thymic selection- need to recognise the MHC, cell death by neglect where this recognition does not occur
filtering for autoreactive cells
testing response to the pathogen- passing activation threshold > can divide

Question 9

how can B cell class switches occur

Answer 9

changes in antibody production at the constant region of Ig- e.g. IgE into IgA

Question 10

difference in what MHCs lead to what T cell being produced

Answer 10

CD4+- MHC II
CD8+- MHC I

Question 11

gammadelta T cells

Answer 11

can do either the cytotoxic or helper functions

Question 12

subdivisions of CD8+ cells

Answer 12

Tc1 and 2, depending on cytokine production

Question 13

subdivision of CD4+ cells

Answer 13

based on cytokine production mostly- e.g. Th17 producing IL-17

Question 14

Treg cell cytokine production

Answer 14

IL-10, inhibits some cytokines so prevents Th activation (12/23)

Question 15

names of different activation pathways

Answer 15

endogenous- MHC I and CD8- involves sampling cytoplasm (but dendritic cells can present extracellular antigens through this process, as they need to)
exogenous- MHC II and CD4- involves sampling extracellular compartment, mostly of APCs

Question 16

3 types of professional APC

Answer 16

dendritic cells, macrophages, B cells

Question 17

CD8 cell terminal phenotype

Answer 17

IFNγ producing cytotoxic capable cells, containing enzymes such as granzymes A and B and perforin

Question 18

differences between individual CD8 cells

Answer 18

different ‘levels’ of the terminal phenotype, e.g. may be ‘single’ - ‘total’ producers

Question 19

3 cytotoxic molecules

Answer 19

granzyme A/B (activate cytotoxic pathways)
perforin (hole)
granylysin (activates apoptosis, direct antibiotic effects)

Question 20

CD4 vs 8 memory

Answer 20

CD8 memory seems more stable
-however may not be universal, found higher selective deletion of CD8 memory cells in a mouse infection (Varga 2001)

Question 21

2 types of CD8 memory pool

Answer 21

effector memory (fast effectors, depleted quicker)
central memory (stick around, but need to proliferate before they can do much)

Question 22

Th1 cells

Answer 22

IL-2 and TFNbeta
activate macrophages

Question 23

Treg cells

Answer 23

IL-20 and TGFbeta
down-regulate other T cell responses

Question 24

how can Th subsets be differentiated

Answer 24

naive cells stimulated with signalling molecules such as IL-12

Question 25

important fact about Th cell differentiation

Answer 25

can be plasticity- reprogramming etc is common

Question 26

another type of TCRαβ cell

Answer 26

invariant natural killer T cells
act as an early source of cytokines like NK cells, but different pathway of activation and no evidence of memory

Question 27

TCRγδ cells- function

Answer 27

recognise different things compared to ab cells
earliest T cells in the thymus- important in early life?