Maturation and Activation of T cells

Question 1

what is RAG

Answer 1

recombination activating gene

Question 2

severe combined immune deficiency (SCID) patients have a mutation in what

Answer 2

RAG1 and RAG2

Question 3

what is TCR

Answer 3

T cell receptor

Question 4

what do TCRs recognize

Answer 4

peptides displayed by MHC molecules

Question 5

T/F TCR on each T cell clone is able to bind many peptides

Answer 5

False. TCR on each T cell clone is specific for a distinct peptide

Question 6

what makes up the immune repertoire?

Answer 6

collection of distinct clones

Question 7

describe the structure of TCR

Answer 7

membrane-bound heterodimeric protein composed of an alpha chain and a beta chain
there is a variable region and a constant region

Question 8

where is the binding site for MHC I molecules

Answer 8

variable domain of alpha chains

Question 9

where is the binding site for MHC II molecules

Answer 9

variable domains of alpha and beta chains

Question 10

what is recognized by the TCR

Answer 10

1-3 residues of the peptides (processed antigen recognized)

Question 11

what accounts for the diversity?

Answer 11

somatic recombination of gene segments

Question 12

within the chains, what does V, D, J, and C stand for

Answer 12

variable
diversity
joining
constant

Question 13

what does the TCR beta chain contain

Answer 13

variable, short diversity, joining and constant gene segments

Question 14

what does the TCR alpha chain contain

Answer 14

variable, joining and constant gene segments. No short diversity

Question 15

where are the D and J gene segments located

Answer 15

between V and C gene segments

Question 16

during recombination are the segments selected precisely or randomly

Answer 16

random

Question 17

what is the recombination mediated by

Answer 17

lymphocyte-specific VDJ recombinase (RAG) that brings two segments close together

Question 18

what are the 3 steps in recombination

Answer 18

1. recombination of D and J segments
2. recombination of V segments with fused D-J element
3. recombination of C segment with fused V-D-J element
   note: no D segment in alpha chain

Question 19

what else leads to the increasing diversity

Answer 19

exonucleases - remove nucleotides
terminal deoxyribonucleotidyl transferase (TdT) - transfers nucleotides

Question 20

where do T cells mature

Answer 20

thymus

Question 21

how can a Pro-T cell be described and what does that mean

Answer 21

double negative
means CD4- and CD8-

Question 22

what promotes cell survival in maturing T cells

Answer 22

pre-TCR and complete TCR

Question 23

how can an immature T cell be described as what does that mean

Answer 23

double positive
means CD4+ and CD8+

Question 24

T/F maturing T cells that do not express functional receptors will die

Answer 24

True. Pre-TCR and TCR are both needed for survival

Question 25

what kind of recognition of MHC+ peptide leads to positive selection

Answer 25

weak recognition

Question 26

what kind of recognition of MHC+ peptide leads to cell death

Answer 26

no recognition and strong recognition

Question 27

weak recognition of class II MHC + peptide leads to what kind of cell

Answer 27

mature CD4+ cell

Question 28

weak recognition of class I MHC + peptide leads to what kind of cell

Answer 28

mature CD8+ cell

Question 29

T/F the appropriate amount of antigen recognition in the thymus allows T cells to be selected and migrate to the periphery

Answer 29

True

Question 30

where do naive T cells circulate in search of antigens

Answer 30

from lymph node to lymph node

Question 31

what occurs after antigen recognition to a naive T cell

Answer 31

proliferation and differentiation

Question 32

After effector T cells migrate to antigen sites in tissues they get:

Answer 32

reactivated and carry their function (to keep cells @ site of infection)

Question 33

T/F antigen recognition (signal 1) alone is sufficient

Answer 33

False. antigen recognition (signal 1) alone induces unresponsiveness

Question 34

what provides signal 2 to induce proliferation of T cells

Answer 34

engagement of B7 (present on surface of APC) by CD28 (present on surface of T cells)

Question 35

what is produced by T cells to help clones proliferate

Answer 35

IL-2

Question 36

what are the three inhibitory signals and their receptors

Answer 36

B7-2 binds to CTLA-4 PD-L1 and PDL-2 bind to PD-1

Question 37

why are the inhibitory receptors important

Answer 37

critical for limiting/terminating immune response

Question 38

how does activation of CD4 T cells provide help to CD8 T cells

Answer 38

IL-2 production. IL-2 produced by CD4 helper T cell

Question 39

T/F antigen-specific T cell clones expand in response to antigen to provide large pool of effector cells to fight infection

Answer 39

True

Question 40

which t cells increase in number the most

Answer 40

CD8 cells

Question 41

where do memory cells reside

Answer 41

lymphoid organs and mucosal and peripheral tissues

Question 42

T/F most effector T cells do not leave LN

Answer 42

False. Most leave the lymph node

Question 43

which T cells do not leave the LN

Answer 43

follicular helper T cells (Tfh) - they help B cells

Question 44

what is the function of CD4 helper T cells in cell-mediated immunity

Answer 44

activate phagocytes via IFNy production and CD40-CD40L

Question 45

where is CD40 present

Answer 45

on macrophage and/or B cell

Question 46

where is CD40L present

Answer 46

on CD4+ T cell

Question 47

what is the function of CD4 helper T cells in humoral imunity

Answer 47

activate B cells to produce Ig via cytokine production and CD40-CD40L

Question 48

what allows for T cell movement

Answer 48

combination of adhesion molecules and chemokine receptor

Question 49

what is S1P

Answer 49

sphingosine 1-phosphate

Question 50

how do T cells exit LN

Answer 50

upregulate S1PR1 and follow S1P gradient (downregulate S1PR1 to stay in LN)