T Cell Development and Effector Function

Question 1

T Cell Receptor

Answer 1

V (D) J recombination
uses RAG proteins
V region has 3 hypervariable regions
TCR remains membrane bound
non class switching or affinity maturation**
majority alpha beta

Question 2

smaller subset of T Cell Receptors?

Answer 2

gamma-delta

**only 5-10%

Question 3

why is it important to have no affinity maturation in T Cell receptor?

Answer 3

increases the likelihood they will recognize a self peptide

this could lead to autoimmunity

Question 4

what does the TCR recognize?

Answer 4

1-3 residues on the MHC-peptide complex

much weaker interaction than with antibodies

Question 5

what is necessary for TCR binding?

Answer 5

binding to both the antigen and the MHC molecule

Question 6

beta chain locus for TCR?

Answer 6

on chromosome 7
includes D regions

**undergo combinatorial and junctional diversity

RAG1 and RAG 2 proteins mediate recombination

Question 7

double negative cell

Answer 7

naive mature T cell that does not express the CD4 or the CD8

Question 8

double positive cell

Answer 8

express both CD4 and CD8 on the cell

Question 9

what will express CD4?

Answer 9

something that interacted with MHC II

Question 10

wha will express CD8?

Answer 10

something that interacted with MHC I

Question 11

what T cells make it to the periphery

Answer 11

those that had weak affinity for MHC and self antigens

Question 12

positive selection

Answer 12

weak interacting TCRs with antigen/MHC are selected to survive

Question 13

negative selection

Answer 13

strong interacting TCRs with antigen/MHC are selected against and undergo apoptosis

Question 14

where does positive and negative selection occur

Answer 14

cortex

Question 15

as maturing T cell moves to the medulla what happens?

Answer 15

becomes single positive

Question 16

MHC restriction

Answer 16

TCR only recognizes an antigen bound to MHC

Question 17

what happens if you can’t express MHC class I

Answer 17

will only have CD4 (no CD8 expression)

Question 18

cell-mediated immunity involves what to processes?

Answer 18

combats intracellular microbes (ingested microbes and viruses

T cells recognize peptides presented in the context of MHC (APC’s and infected host cells)

Question 19

APCs express what MHC?

Answer 19

MHC class II (also Class I)

Question 20

what cells express MHC class I?

Answer 20

all nucleated cells

Question 21

what happens when naive CD4 cells are activated?

Answer 21

change their IL-2 receptor to higher affinity

can undergo clonal expansion and mature to effector or memory CD4 T cells

Question 22

what do you need to make sure if you remove a patient’s spleen?

Answer 22

that they are up to date on their immunizations

Question 23

what makes up the TCR complex?

Answer 23

CD3, zeta chain, and TCR

on all the T cells

Question 24

CD28

Answer 24

interacts with B7 molecules on APC
this increases IL-2 production
activate the T cell
after T cells have been activated, the CTLA-4 is increased - inhibitory structure

Question 25

CTLA-4

Answer 25

outcompetes the CD28 and decreases IL-2 production

Question 26

cross-presentation

Answer 26

dendritic cell can place antigens on MHC class I and II CD4 secretes cytokines that help to activate the CD8 cells

Question 27

activation of CD8 T cells

Answer 27

can be activated directly but also by cross-presentation CD-4 cytokines

Question 28

CD40L

Answer 28

helps to prolong the interaction of the T cell with the APC

Question 29

what happens to IL-2 receptor during activation?

Answer 29

increases its affinity for IL-2

Question 30

IL-2

Answer 30

survival, differentiation of the CD4 and CD8 T cells

Question 31

TGF-beta

Answer 31

inhibition of T cell activation

Question 32

IL-4

Answer 32

switches B cell to IgE | **Th2

Question 33

IL-5

Answer 33

activation of eosinophils | **Th2

Question 34

Interferon-gamma

Answer 34

activation of macrophages

Question 35

what would happen after you block CTLA-4 action?

Answer 35

would not be able to inhibit the T cell proliferation and they would always stay on **may be beneficial in anti-cancer therapy side-effects: autoimmunity

Question 36

types of CD4 T cells?

Answer 36

Th2, Th1, Th17, T regulatory cells

Question 37

Th1 cells

Answer 37

produce IFN-gamma | activate macrophages

Question 38

Th2 cells

Answer 38

produce IL-4, IL-5, and IL-13 | promote humoral immunity

Question 39

Th17 cells

Answer 39

produce IL-17 | involved in host defense AND pathogenesis of autoimmune disease

Question 40

T regulatory cells

Answer 40

suppress the T cell function

Question 41

CD40L

Answer 41

on the CD4 T cells that interacts with CD40 on macrophage leads to macrophage activation

Question 42

what happens with asthma (which T cells)?

Answer 42

Th2 which activates eosinophils and mast cells

Question 43

what activates Th1 formation?

Answer 43

IL-12 and IFN-gamma

Question 44

what activation Th17 formation?

Answer 44

``` IL-6** TGF-beta IL-1 IL-23 GM-CSF ```

Question 45

what activates Th2 formation?

Answer 45

TSLP

Question 46

what do Th1 cells do?

Answer 46

secrete IFN-gamma also produce TNF-alpha

Question 47

what does IFN-gamme release from Th1 cells cause?

Answer 47

activation of macrophages stimulation of complement binding Class II MHC and B7 expression

Question 48

what may lead to multiple sclerosis?

Answer 48

Th1 response

Question 49

what does the classical macrophage activation lead to?

Answer 49

enhance microbial killing

Question 50

what do Th2 cells release?

Answer 50

IL-4, IL-5, and IL-13

Question 51

IL-4

Answer 51

- activate B cells to produce IgE | - also activate the macrophage to increase fibrosis/tissue repair (alternative)

Question 52

IL-5

Answer 52

activate eosinophils

Question 53

alternative macrophage activation?

Answer 53

leads to fibrosis and tissue repair | **stimulated by IL-4 and IL-13

Question 54

Th17

Answer 54

secretes IL-17

Question 55

IL-17

Answer 55

recruits the leukocytes to sites of infection | functions to maintain epithelial barrier and important in gut tolerance

Question 56

phagocyte with ingested microbes causes what?

Answer 56

``` MHC class II presented antigens activates Th1 and Th17 CD4 T cells ```

Question 57

infected cell with cytoplasm microbes causes what?

Answer 57

``` MHC class presented antigens activates the CD8 T cells ```

Question 58

what adhesion molecules move T cells to the lymph node?

Answer 58

expression of L selectin and LFA-1 and CCR7 on naive T cells

Question 59

what adhesion molecules move T cells to sites of infection?

Answer 59

E and P selectin, LFA-1 and VLA-4 and CXCR3 (chemokines) ** T cells get to where they need by homing signals

Question 60

what activates a naive CD4 cell to become Th1?

Answer 60

IL-12 dependent on antigen-recognition basis for delayed-type hypersensitivity reaction

Question 61

macrophage activation by Th1 cells?

Answer 61

increases ROS and NO, secretes cytokines TNF, IL-1, IL-12, increased MHC and B7

Question 62

PPD test?

Answer 62

example of a Delayed-type hypersensitivity reaction of the Th1 activation

Question 63

balance between the Th1 and Th2 cells?

Answer 63

Th2 cell cytokines shuts down the classical activation of macrophages (microbicidal) defects in either can cause problems ex/ leprosy

Question 64

what happens with CD8 T cell activation?

Answer 64

secretion of granzymes and perforins perforins poke holes and granzymes enter and activate the caspases > apoptosis

Question 65

cooperation between the CD4 and CD8?

Answer 65

yeah.