T cells

Question 1

2 types of T-cells and their functions

Answer 1

CD4 - help other immune cells respond to EXTRAcellular infections
CD8 - kills cells that have become virally infected

Question 2

what is process of cognate interaction

Answer 2

1. antigen recognition of Tfh cell induces expression of CD40 ligand and cytokines
2. these work together to activate B-cell
3. B-cell proliferates

Question 3

2 requirements for macrophage activation

Answer 3

1. IFN-y produced by TH1 cell

2. CD40 ligand on T cell binds to CD40 on macrophage

Question 4

what are 2 T-cell receptors and which is most common

Answer 4

a: B - common
y: d - not sure what it does

Question 5

what are a:B subdivisions

Answer 5

CD4 and CD8

Question 6

how does T cell receptor dev.

Answer 6

somatic recombination - V-J rearrangement

Question 7

where does T-cell stages occur

Answer 7

1. dev in marrow
2. recombination in thymus
3. travel to secondary lymph nodes

Question 8

how is antigen presented to a T-cell

Answer 8

broken up and put onto an MHC molecule

Question 9

what is MHC

Answer 9

specialized antigen presenting glycoproteins

Question 10

what is MHC specificity

Answer 10

can bind multiple different antigens as long as the AA “anchor” is the same

Question 11

what is T-cell specificity

Answer 11

T-cell can only recognize single antigen and only when bound to MHC

Question 12

what are 2 classes of MHC molecules, examples, and where found

Answer 12

1. HLA A,B,C - most nucleated cells

2. HLA Ds - only on antigen presenting cells

Question 13

which MHC correspond to which CD

Answer 13

CD8 - 1

CD4 – 2

Question 14

how is MHC changeable

Answer 14

MHC is stable and inherited

Question 15

what is antigen processing

Answer 15

method by which pathogens are broken down to be presented on MHC to T-cell

Question 16

basic steps to pathogen processing

Answer 16

1. dendritic cells take up pathogen
2. taken apart in DC
3. cut up
4. put on MHC in cell
5. MHC put on the outside

Question 17

what is mech of intracellular pathogen

Answer 17

1. antigen processed in cell in proteosome
2. peptide transported to ER
3. bound to MHC in ER
4. placed on cell surface with MHC

Question 18

what is mech of extracellular pathogen

Answer 18

1. pathogen endocytosed
2. degraded with endolysosome
3. MHC is made in golgi and put in vesicle
4. pathogen and MHC vesicles combined
5. MHC placed on cell surface

Question 19

3 stages of T=cell maturation in thymus

Answer 19

1. gene rearrangement in cortex
2. positive selection
3. negative selection

Question 20

what is order of gene rearragment

Answer 20

1. D-JB
2. V-DJ
3. V-Ja

Question 21

what occurs in double negative stage

Answer 21

1. T-cell progenitor rearranges to make TCR
2. if TCR made - passes checkpoint
3. proliferates and enter double pos. stage

Question 22

what occurs in double pos. stage

Answer 22

1. rearrange again to make CD4 and CD8 receptor

2. pass checkpoint

Question 23

2 types of screening that double pos. Tcells undergo

Answer 23

1. positive selection - ID cells restricted to self-MHC

2. negative - ID and elim those cells that react to self antigen

Question 24

2 main functions of pos. selction

Answer 24

1. test for self MHC recognition
2. depending on class of MHC recognized, will tell whether is a CD4 or CD8 - will stop expressing non-binding co-receptor

Question 25

3 things that are presented to T-cell in negative selection

Answer 25

1. peptide made from proteins made by DCs 2. peptides from cell phaged by macrophages 3. soluble proteins taken up by extracellular proteins

Question 26

how does T-cell get tested for self-antigen binding

Answer 26

AIRE - transcription factor that causes several hundred tissue specific genes to be transcribed by sub-population in thymic medulla - bound to MHC 1 for help with negative selection

Question 27

what are problems with central tolerance

Answer 27

1. some self-peptides not found in thymus | 2. this means these won't be negatively selected

Question 28

what does thymic selection do

Answer 28

give each person and unique T-cell repertoire

Question 29

how do mature T-cells know where to go

Answer 29

can go to node from lymph or blood vessels – chemokines

Question 30

what happens when a T-cell encounters its antigens

Answer 30

proliferates and becomes an effector t-cell

Question 31

how is T-cell activated

Answer 31

1. must find APC 2. TCR must bind MHC 3. second co-stimulation also required to activate T-cell